From 00c9709fd9763542e848f6278db8ba26af5c9886 Mon Sep 17 00:00:00 2001
From: Max
Date: Mon, 15 Oct 2018 23:46:42 +0200
Subject: Initial commit.

---
 src/sass/bootstrap4/_alert.scss                    |  51 ++
 src/sass/bootstrap4/_badge.scss                    |  47 +
 src/sass/bootstrap4/_breadcrumb.scss               |  41 +
 src/sass/bootstrap4/_button-group.scss             | 172 ++++
 src/sass/bootstrap4/_buttons.scss                  | 143 ++++
 src/sass/bootstrap4/_card.scss                     | 301 +++++++
 src/sass/bootstrap4/_carousel.scss                 | 236 +++++
 src/sass/bootstrap4/_close.scss                    |  35 +
 src/sass/bootstrap4/_code.scss                     |  48 ++
 src/sass/bootstrap4/_custom-forms.scss             | 433 ++++++++++
 src/sass/bootstrap4/_dropdown.scss                 | 166 ++++
 src/sass/bootstrap4/_forms.scss                    | 333 +++++++
 src/sass/bootstrap4/_functions.scss                |  86 ++
 src/sass/bootstrap4/_grid.scss                     |  52 ++
 src/sass/bootstrap4/_images.scss                   |  42 +
 src/sass/bootstrap4/_input-group.scss              | 173 ++++
 src/sass/bootstrap4/_jumbotron.scss                |  16 +
 src/sass/bootstrap4/_list-group.scss               | 115 +++
 src/sass/bootstrap4/_media.scss                    |   8 +
 src/sass/bootstrap4/_mixins.scss                   |  41 +
 src/sass/bootstrap4/_modal.scss                    | 180 ++++
 src/sass/bootstrap4/_nav.scss                      | 118 +++
 src/sass/bootstrap4/_navbar.scss                   | 299 +++++++
 src/sass/bootstrap4/_pagination.scss               |  78 ++
 src/sass/bootstrap4/_popover.scss                  | 183 ++++
 src/sass/bootstrap4/_print.scss                    | 141 +++
 src/sass/bootstrap4/_progress.scss                 |  34 +
 src/sass/bootstrap4/_reboot.scss                   | 483 +++++++++++
 src/sass/bootstrap4/_root.scss                     |  19 +
 src/sass/bootstrap4/_tables.scss                   | 187 ++++
 src/sass/bootstrap4/_tooltip.scss                  | 115 +++
 src/sass/bootstrap4/_transitions.scss              |  22 +
 src/sass/bootstrap4/_type.scss                     | 125 +++
 src/sass/bootstrap4/_utilities.scss                |  15 +
 src/sass/bootstrap4/_variables.scss                | 952 +++++++++++++++++++++
 src/sass/bootstrap4/bootstrap-grid.scss            |  32 +
 src/sass/bootstrap4/bootstrap-reboot.scss          |  12 +
 src/sass/bootstrap4/bootstrap.scss                 |  42 +
 src/sass/bootstrap4/mixins/_alert.scss             |  13 +
 .../bootstrap4/mixins/_background-variant.scss     |  21 +
 src/sass/bootstrap4/mixins/_badge.scss             |  12 +
 src/sass/bootstrap4/mixins/_border-radius.scss     |  35 +
 src/sass/bootstrap4/mixins/_box-shadow.scss        |   5 +
 src/sass/bootstrap4/mixins/_breakpoints.scss       | 123 +++
 src/sass/bootstrap4/mixins/_buttons.scss           | 109 +++
 src/sass/bootstrap4/mixins/_caret.scss             |  66 ++
 src/sass/bootstrap4/mixins/_clearfix.scss          |   7 +
 src/sass/bootstrap4/mixins/_float.scss             |  11 +
 src/sass/bootstrap4/mixins/_forms.scss             | 147 ++++
 src/sass/bootstrap4/mixins/_gradients.scss         |  45 +
 src/sass/bootstrap4/mixins/_grid-framework.scss    |  67 ++
 src/sass/bootstrap4/mixins/_grid.scss              |  52 ++
 src/sass/bootstrap4/mixins/_hover.scss             |  37 +
 src/sass/bootstrap4/mixins/_image.scss             |  36 +
 src/sass/bootstrap4/mixins/_list-group.scss        |  21 +
 src/sass/bootstrap4/mixins/_lists.scss             |   7 +
 src/sass/bootstrap4/mixins/_nav-divider.scss       |  10 +
 src/sass/bootstrap4/mixins/_pagination.scss        |  22 +
 src/sass/bootstrap4/mixins/_reset-text.scss        |  17 +
 src/sass/bootstrap4/mixins/_resize.scss            |   6 +
 src/sass/bootstrap4/mixins/_screen-reader.scss     |  33 +
 src/sass/bootstrap4/mixins/_size.scss              |   6 +
 src/sass/bootstrap4/mixins/_table-row.scss         |  30 +
 src/sass/bootstrap4/mixins/_text-emphasis.scss     |  14 +
 src/sass/bootstrap4/mixins/_text-hide.scss         |  13 +
 src/sass/bootstrap4/mixins/_text-truncate.scss     |   8 +
 src/sass/bootstrap4/mixins/_transition.scss        |  13 +
 src/sass/bootstrap4/mixins/_visibility.scss        |   7 +
 src/sass/bootstrap4/utilities/_align.scss          |   8 +
 src/sass/bootstrap4/utilities/_background.scss     |  19 +
 src/sass/bootstrap4/utilities/_borders.scss        |  59 ++
 src/sass/bootstrap4/utilities/_clearfix.scss       |   3 +
 src/sass/bootstrap4/utilities/_display.scss        |  38 +
 src/sass/bootstrap4/utilities/_embed.scss          |  52 ++
 src/sass/bootstrap4/utilities/_flex.scss           |  51 ++
 src/sass/bootstrap4/utilities/_float.scss          |   9 +
 src/sass/bootstrap4/utilities/_position.scss       |  37 +
 src/sass/bootstrap4/utilities/_screenreaders.scss  |  11 +
 src/sass/bootstrap4/utilities/_shadows.scss        |   6 +
 src/sass/bootstrap4/utilities/_sizing.scss         |  12 +
 src/sass/bootstrap4/utilities/_spacing.scss        |  51 ++
 src/sass/bootstrap4/utilities/_text.scss           |  58 ++
 src/sass/bootstrap4/utilities/_visibility.scss     |  11 +
 83 files changed, 6994 insertions(+)
 create mode 100644 src/sass/bootstrap4/_alert.scss
 create mode 100644 src/sass/bootstrap4/_badge.scss
 create mode 100644 src/sass/bootstrap4/_breadcrumb.scss
 create mode 100644 src/sass/bootstrap4/_button-group.scss
 create mode 100644 src/sass/bootstrap4/_buttons.scss
 create mode 100644 src/sass/bootstrap4/_card.scss
 create mode 100644 src/sass/bootstrap4/_carousel.scss
 create mode 100644 src/sass/bootstrap4/_close.scss
 create mode 100644 src/sass/bootstrap4/_code.scss
 create mode 100644 src/sass/bootstrap4/_custom-forms.scss
 create mode 100644 src/sass/bootstrap4/_dropdown.scss
 create mode 100644 src/sass/bootstrap4/_forms.scss
 create mode 100644 src/sass/bootstrap4/_functions.scss
 create mode 100644 src/sass/bootstrap4/_grid.scss
 create mode 100644 src/sass/bootstrap4/_images.scss
 create mode 100644 src/sass/bootstrap4/_input-group.scss
 create mode 100644 src/sass/bootstrap4/_jumbotron.scss
 create mode 100644 src/sass/bootstrap4/_list-group.scss
 create mode 100644 src/sass/bootstrap4/_media.scss
 create mode 100644 src/sass/bootstrap4/_mixins.scss
 create mode 100644 src/sass/bootstrap4/_modal.scss
 create mode 100644 src/sass/bootstrap4/_nav.scss
 create mode 100644 src/sass/bootstrap4/_navbar.scss
 create mode 100644 src/sass/bootstrap4/_pagination.scss
 create mode 100644 src/sass/bootstrap4/_popover.scss
 create mode 100644 src/sass/bootstrap4/_print.scss
 create mode 100644 src/sass/bootstrap4/_progress.scss
 create mode 100644 src/sass/bootstrap4/_reboot.scss
 create mode 100644 src/sass/bootstrap4/_root.scss
 create mode 100644 src/sass/bootstrap4/_tables.scss
 create mode 100644 src/sass/bootstrap4/_tooltip.scss
 create mode 100644 src/sass/bootstrap4/_transitions.scss
 create mode 100644 src/sass/bootstrap4/_type.scss
 create mode 100644 src/sass/bootstrap4/_utilities.scss
 create mode 100644 src/sass/bootstrap4/_variables.scss
 create mode 100644 src/sass/bootstrap4/bootstrap-grid.scss
 create mode 100644 src/sass/bootstrap4/bootstrap-reboot.scss
 create mode 100644 src/sass/bootstrap4/bootstrap.scss
 create mode 100644 src/sass/bootstrap4/mixins/_alert.scss
 create mode 100644 src/sass/bootstrap4/mixins/_background-variant.scss
 create mode 100644 src/sass/bootstrap4/mixins/_badge.scss
 create mode 100644 src/sass/bootstrap4/mixins/_border-radius.scss
 create mode 100644 src/sass/bootstrap4/mixins/_box-shadow.scss
 create mode 100644 src/sass/bootstrap4/mixins/_breakpoints.scss
 create mode 100644 src/sass/bootstrap4/mixins/_buttons.scss
 create mode 100644 src/sass/bootstrap4/mixins/_caret.scss
 create mode 100644 src/sass/bootstrap4/mixins/_clearfix.scss
 create mode 100644 src/sass/bootstrap4/mixins/_float.scss
 create mode 100644 src/sass/bootstrap4/mixins/_forms.scss
 create mode 100644 src/sass/bootstrap4/mixins/_gradients.scss
 create mode 100644 src/sass/bootstrap4/mixins/_grid-framework.scss
 create mode 100644 src/sass/bootstrap4/mixins/_grid.scss
 create mode 100644 src/sass/bootstrap4/mixins/_hover.scss
 create mode 100644 src/sass/bootstrap4/mixins/_image.scss
 create mode 100644 src/sass/bootstrap4/mixins/_list-group.scss
 create mode 100644 src/sass/bootstrap4/mixins/_lists.scss
 create mode 100644 src/sass/bootstrap4/mixins/_nav-divider.scss
 create mode 100644 src/sass/bootstrap4/mixins/_pagination.scss
 create mode 100644 src/sass/bootstrap4/mixins/_reset-text.scss
 create mode 100644 src/sass/bootstrap4/mixins/_resize.scss
 create mode 100644 src/sass/bootstrap4/mixins/_screen-reader.scss
 create mode 100644 src/sass/bootstrap4/mixins/_size.scss
 create mode 100644 src/sass/bootstrap4/mixins/_table-row.scss
 create mode 100644 src/sass/bootstrap4/mixins/_text-emphasis.scss
 create mode 100644 src/sass/bootstrap4/mixins/_text-hide.scss
 create mode 100644 src/sass/bootstrap4/mixins/_text-truncate.scss
 create mode 100644 src/sass/bootstrap4/mixins/_transition.scss
 create mode 100644 src/sass/bootstrap4/mixins/_visibility.scss
 create mode 100644 src/sass/bootstrap4/utilities/_align.scss
 create mode 100644 src/sass/bootstrap4/utilities/_background.scss
 create mode 100644 src/sass/bootstrap4/utilities/_borders.scss
 create mode 100644 src/sass/bootstrap4/utilities/_clearfix.scss
 create mode 100644 src/sass/bootstrap4/utilities/_display.scss
 create mode 100644 src/sass/bootstrap4/utilities/_embed.scss
 create mode 100644 src/sass/bootstrap4/utilities/_flex.scss
 create mode 100644 src/sass/bootstrap4/utilities/_float.scss
 create mode 100644 src/sass/bootstrap4/utilities/_position.scss
 create mode 100644 src/sass/bootstrap4/utilities/_screenreaders.scss
 create mode 100644 src/sass/bootstrap4/utilities/_shadows.scss
 create mode 100644 src/sass/bootstrap4/utilities/_sizing.scss
 create mode 100644 src/sass/bootstrap4/utilities/_spacing.scss
 create mode 100644 src/sass/bootstrap4/utilities/_text.scss
 create mode 100644 src/sass/bootstrap4/utilities/_visibility.scss

(limited to 'src/sass/bootstrap4')

diff --git a/src/sass/bootstrap4/_alert.scss b/src/sass/bootstrap4/_alert.scss
new file mode 100644
index 0000000..dd43e23
--- /dev/null
+++ b/src/sass/bootstrap4/_alert.scss
@@ -0,0 +1,51 @@
+//
+// Base styles
+//
+
+.alert {
+  position: relative;
+  padding: $alert-padding-y $alert-padding-x;
+  margin-bottom: $alert-margin-bottom;
+  border: $alert-border-width solid transparent;
+  @include border-radius($alert-border-radius);
+}
+
+// Headings for larger alerts
+.alert-heading {
+  // Specified to prevent conflicts of changing $headings-color
+  color: inherit;
+}
+
+// Provide class for links that match alerts
+.alert-link {
+  font-weight: $alert-link-font-weight;
+}
+
+
+// Dismissible alerts
+//
+// Expand the right padding and account for the close button's positioning.
+
+.alert-dismissible {
+  padding-right: ($close-font-size + $alert-padding-x * 2);
+
+  // Adjust close link position
+  .close {
+    position: absolute;
+    top: 0;
+    right: 0;
+    padding: $alert-padding-y $alert-padding-x;
+    color: inherit;
+  }
+}
+
+
+// Alternate styles
+//
+// Generate contextual modifier classes for colorizing the alert.
+
+@each $color, $value in $theme-colors {
+  .alert-#{$color} {
+    @include alert-variant(theme-color-level($color, $alert-bg-level), theme-color-level($color, $alert-border-level), theme-color-level($color, $alert-color-level));
+  }
+}
diff --git a/src/sass/bootstrap4/_badge.scss b/src/sass/bootstrap4/_badge.scss
new file mode 100644
index 0000000..b87a1b0
--- /dev/null
+++ b/src/sass/bootstrap4/_badge.scss
@@ -0,0 +1,47 @@
+// Base class
+//
+// Requires one of the contextual, color modifier classes for `color` and
+// `background-color`.
+
+.badge {
+  display: inline-block;
+  padding: $badge-padding-y $badge-padding-x;
+  font-size: $badge-font-size;
+  font-weight: $badge-font-weight;
+  line-height: 1;
+  text-align: center;
+  white-space: nowrap;
+  vertical-align: baseline;
+  @include border-radius($badge-border-radius);
+
+  // Empty badges collapse automatically
+  &:empty {
+    display: none;
+  }
+}
+
+// Quick fix for badges in buttons
+.btn .badge {
+  position: relative;
+  top: -1px;
+}
+
+// Pill badges
+//
+// Make them extra rounded with a modifier to replace v3's badges.
+
+.badge-pill {
+  padding-right: $badge-pill-padding-x;
+  padding-left: $badge-pill-padding-x;
+  @include border-radius($badge-pill-border-radius);
+}
+
+// Colors
+//
+// Contextual variations (linked badges get darker on :hover).
+
+@each $color, $value in $theme-colors {
+  .badge-#{$color} {
+    @include badge-variant($value);
+  }
+}
diff --git a/src/sass/bootstrap4/_breadcrumb.scss b/src/sass/bootstrap4/_breadcrumb.scss
new file mode 100644
index 0000000..be30950
--- /dev/null
+++ b/src/sass/bootstrap4/_breadcrumb.scss
@@ -0,0 +1,41 @@
+.breadcrumb {
+  display: flex;
+  flex-wrap: wrap;
+  padding: $breadcrumb-padding-y $breadcrumb-padding-x;
+  margin-bottom: $breadcrumb-margin-bottom;
+  list-style: none;
+  background-color: $breadcrumb-bg;
+  @include border-radius($breadcrumb-border-radius);
+}
+
+.breadcrumb-item {
+  // The separator between breadcrumbs (by default, a forward-slash: "/")
+  + .breadcrumb-item {
+    padding-left: $breadcrumb-item-padding;
+
+    &::before {
+      display: inline-block; // Suppress underlining of the separator in modern browsers
+      padding-right: $breadcrumb-item-padding;
+      color: $breadcrumb-divider-color;
+      content: $breadcrumb-divider;
+    }
+  }
+
+  // IE9-11 hack to properly handle hyperlink underlines for breadcrumbs built
+  // without `<ul>`s. The `::before` pseudo-element generates an element
+  // *within* the .breadcrumb-item and thereby inherits the `text-decoration`.
+  //
+  // To trick IE into suppressing the underline, we give the pseudo-element an
+  // underline and then immediately remove it.
+  + .breadcrumb-item:hover::before {
+    text-decoration: underline;
+  }
+  // stylelint-disable-next-line no-duplicate-selectors
+  + .breadcrumb-item:hover::before {
+    text-decoration: none;
+  }
+
+  &.active {
+    color: $breadcrumb-active-color;
+  }
+}
diff --git a/src/sass/bootstrap4/_button-group.scss b/src/sass/bootstrap4/_button-group.scss
new file mode 100644
index 0000000..5495170
--- /dev/null
+++ b/src/sass/bootstrap4/_button-group.scss
@@ -0,0 +1,172 @@
+// stylelint-disable selector-no-qualifying-type
+
+// Make the div behave like a button
+.btn-group,
+.btn-group-vertical {
+  position: relative;
+  display: inline-flex;
+  vertical-align: middle; // match .btn alignment given font-size hack above
+
+  > .btn {
+    position: relative;
+    flex: 0 1 auto;
+
+    // Bring the hover, focused, and "active" buttons to the front to overlay
+    // the borders properly
+    @include hover {
+      z-index: 1;
+    }
+    &:focus,
+    &:active,
+    &.active {
+      z-index: 1;
+    }
+  }
+
+  // Prevent double borders when buttons are next to each other
+  .btn + .btn,
+  .btn + .btn-group,
+  .btn-group + .btn,
+  .btn-group + .btn-group {
+    margin-left: -$btn-border-width;
+  }
+}
+
+// Optional: Group multiple button groups together for a toolbar
+.btn-toolbar {
+  display: flex;
+  flex-wrap: wrap;
+  justify-content: flex-start;
+
+  .input-group {
+    width: auto;
+  }
+}
+
+.btn-group {
+  > .btn:first-child {
+    margin-left: 0;
+  }
+
+  // Reset rounded corners
+  > .btn:not(:last-child):not(.dropdown-toggle),
+  > .btn-group:not(:last-child) > .btn {
+    @include border-right-radius(0);
+  }
+
+  > .btn:not(:first-child),
+  > .btn-group:not(:first-child) > .btn {
+    @include border-left-radius(0);
+  }
+}
+
+// Sizing
+//
+// Remix the default button sizing classes into new ones for easier manipulation.
+
+.btn-group-sm > .btn { @extend .btn-sm; }
+.btn-group-lg > .btn { @extend .btn-lg; }
+
+
+//
+// Split button dropdowns
+//
+
+.dropdown-toggle-split {
+  padding-right: $btn-padding-x * .75;
+  padding-left: $btn-padding-x * .75;
+
+  &::after,
+  .dropup &::after,
+  .dropright &::after {
+    margin-left: 0;
+  }
+
+  .dropleft &::before {
+    margin-right: 0;
+  }
+}
+
+.btn-sm + .dropdown-toggle-split {
+  padding-right: $btn-padding-x-sm * .75;
+  padding-left: $btn-padding-x-sm * .75;
+}
+
+.btn-lg + .dropdown-toggle-split {
+  padding-right: $btn-padding-x-lg * .75;
+  padding-left: $btn-padding-x-lg * .75;
+}
+
+
+// The clickable button for toggling the menu
+// Set the same inset shadow as the :active state
+.btn-group.show .dropdown-toggle {
+  @include box-shadow($btn-active-box-shadow);
+
+  // Show no shadow for `.btn-link` since it has no other button styles.
+  &.btn-link {
+    @include box-shadow(none);
+  }
+}
+
+
+//
+// Vertical button groups
+//
+
+.btn-group-vertical {
+  flex-direction: column;
+  align-items: flex-start;
+  justify-content: center;
+
+  .btn,
+  .btn-group {
+    width: 100%;
+  }
+
+  > .btn + .btn,
+  > .btn + .btn-group,
+  > .btn-group + .btn,
+  > .btn-group + .btn-group {
+    margin-top: -$btn-border-width;
+    margin-left: 0;
+  }
+
+  // Reset rounded corners
+  > .btn:not(:last-child):not(.dropdown-toggle),
+  > .btn-group:not(:last-child) > .btn {
+    @include border-bottom-radius(0);
+  }
+
+  > .btn:not(:first-child),
+  > .btn-group:not(:first-child) > .btn {
+    @include border-top-radius(0);
+  }
+}
+
+
+// Checkbox and radio options
+//
+// In order to support the browser's form validation feedback, powered by the
+// `required` attribute, we have to "hide" the inputs via `clip`. We cannot use
+// `display: none;` or `visibility: hidden;` as that also hides the popover.
+// Simply visually hiding the inputs via `opacity` would leave them clickable in
+// certain cases which is prevented by using `clip` and `pointer-events`.
+// This way, we ensure a DOM element is visible to position the popover from.
+//
+// See https://github.com/twbs/bootstrap/pull/12794 and
+// https://github.com/twbs/bootstrap/pull/14559 for more information.
+
+.btn-group-toggle {
+  > .btn,
+  > .btn-group > .btn {
+    margin-bottom: 0; // Override default `<label>` value
+
+    input[type="radio"],
+    input[type="checkbox"] {
+      position: absolute;
+      clip: rect(0, 0, 0, 0);
+      pointer-events: none;
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/_buttons.scss b/src/sass/bootstrap4/_buttons.scss
new file mode 100644
index 0000000..0a8eaa9
--- /dev/null
+++ b/src/sass/bootstrap4/_buttons.scss
@@ -0,0 +1,143 @@
+// stylelint-disable selector-no-qualifying-type
+
+//
+// Base styles
+//
+
+.btn {
+  display: inline-block;
+  font-weight: $btn-font-weight;
+  text-align: center;
+  white-space: nowrap;
+  vertical-align: middle;
+  user-select: none;
+  border: $btn-border-width solid transparent;
+  @include button-size($btn-padding-y, $btn-padding-x, $font-size-base, $btn-line-height, $btn-border-radius);
+  @include transition($btn-transition);
+
+  // Share hover and focus styles
+  @include hover-focus {
+    text-decoration: none;
+  }
+
+  &:focus,
+  &.focus {
+    outline: 0;
+    box-shadow: $btn-focus-box-shadow;
+  }
+
+  // Disabled comes first so active can properly restyle
+  &.disabled,
+  &:disabled {
+    opacity: $btn-disabled-opacity;
+    @include box-shadow(none);
+  }
+
+  // Opinionated: add "hand" cursor to non-disabled .btn elements
+  &:not(:disabled):not(.disabled) {
+    cursor: pointer;
+  }
+
+  &:not(:disabled):not(.disabled):active,
+  &:not(:disabled):not(.disabled).active {
+    @include box-shadow($btn-active-box-shadow);
+
+    &:focus {
+      @include box-shadow($btn-focus-box-shadow, $btn-active-box-shadow);
+    }
+  }
+}
+
+// Future-proof disabling of clicks on `<a>` elements
+a.btn.disabled,
+fieldset:disabled a.btn {
+  pointer-events: none;
+}
+
+
+//
+// Alternate buttons
+//
+
+@each $color, $value in $theme-colors {
+  .btn-#{$color} {
+    @include button-variant($value, $value);
+  }
+}
+
+@each $color, $value in $theme-colors {
+  .btn-outline-#{$color} {
+    @include button-outline-variant($value);
+  }
+}
+
+
+//
+// Link buttons
+//
+
+// Make a button look and behave like a link
+.btn-link {
+  font-weight: $font-weight-normal;
+  color: $link-color;
+  background-color: transparent;
+
+  @include hover {
+    color: $link-hover-color;
+    text-decoration: $link-hover-decoration;
+    background-color: transparent;
+    border-color: transparent;
+  }
+
+  &:focus,
+  &.focus {
+    text-decoration: $link-hover-decoration;
+    border-color: transparent;
+    box-shadow: none;
+  }
+
+  &:disabled,
+  &.disabled {
+    color: $btn-link-disabled-color;
+    pointer-events: none;
+  }
+
+  // No need for an active state here
+}
+
+
+//
+// Button Sizes
+//
+
+.btn-lg {
+  @include button-size($btn-padding-y-lg, $btn-padding-x-lg, $font-size-lg, $btn-line-height-lg, $btn-border-radius-lg);
+}
+
+.btn-sm {
+  @include button-size($btn-padding-y-sm, $btn-padding-x-sm, $font-size-sm, $btn-line-height-sm, $btn-border-radius-sm);
+}
+
+
+//
+// Block button
+//
+
+.btn-block {
+  display: block;
+  width: 100%;
+
+  // Vertically space out multiple block buttons
+  + .btn-block {
+    margin-top: $btn-block-spacing-y;
+  }
+}
+
+// Specificity overrides
+input[type="submit"],
+input[type="reset"],
+input[type="button"] {
+  &.btn-block {
+    width: 100%;
+  }
+}
diff --git a/src/sass/bootstrap4/_card.scss b/src/sass/bootstrap4/_card.scss
new file mode 100644
index 0000000..28d7e62
--- /dev/null
+++ b/src/sass/bootstrap4/_card.scss
@@ -0,0 +1,301 @@
+//
+// Base styles
+//
+
+.card {
+  position: relative;
+  display: flex;
+  flex-direction: column;
+  min-width: 0;
+  word-wrap: break-word;
+  background-color: $card-bg;
+  background-clip: border-box;
+  border: $card-border-width solid $card-border-color;
+  @include border-radius($card-border-radius);
+
+  > hr {
+    margin-right: 0;
+    margin-left: 0;
+  }
+
+  > .list-group:first-child {
+    .list-group-item:first-child {
+      @include border-top-radius($card-border-radius);
+    }
+  }
+
+  > .list-group:last-child {
+    .list-group-item:last-child {
+      @include border-bottom-radius($card-border-radius);
+    }
+  }
+}
+
+.card-body {
+  // Enable `flex-grow: 1` for decks and groups so that card blocks take up
+  // as much space as possible, ensuring footers are aligned to the bottom.
+  flex: 1 1 auto;
+  padding: $card-spacer-x;
+}
+
+.card-title {
+  margin-bottom: $card-spacer-y;
+}
+
+.card-subtitle {
+  margin-top: -($card-spacer-y / 2);
+  margin-bottom: 0;
+}
+
+.card-text:last-child {
+  margin-bottom: 0;
+}
+
+.card-link {
+  @include hover {
+    text-decoration: none;
+  }
+
+  + .card-link {
+    margin-left: $card-spacer-x;
+  }
+}
+
+//
+// Optional textual caps
+//
+
+.card-header {
+  padding: $card-spacer-y $card-spacer-x;
+  margin-bottom: 0; // Removes the default margin-bottom of <hN>
+  background-color: $card-cap-bg;
+  border-bottom: $card-border-width solid $card-border-color;
+
+  &:first-child {
+    @include border-radius($card-inner-border-radius $card-inner-border-radius 0 0);
+  }
+
+  + .list-group {
+    .list-group-item:first-child {
+      border-top: 0;
+    }
+  }
+}
+
+.card-footer {
+  padding: $card-spacer-y $card-spacer-x;
+  background-color: $card-cap-bg;
+  border-top: $card-border-width solid $card-border-color;
+
+  &:last-child {
+    @include border-radius(0 0 $card-inner-border-radius $card-inner-border-radius);
+  }
+}
+
+
+//
+// Header navs
+//
+
+.card-header-tabs {
+  margin-right: -($card-spacer-x / 2);
+  margin-bottom: -$card-spacer-y;
+  margin-left: -($card-spacer-x / 2);
+  border-bottom: 0;
+}
+
+.card-header-pills {
+  margin-right: -($card-spacer-x / 2);
+  margin-left: -($card-spacer-x / 2);
+}
+
+// Card image
+.card-img-overlay {
+  position: absolute;
+  top: 0;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  padding: $card-img-overlay-padding;
+}
+
+.card-img {
+  width: 100%; // Required because we use flexbox and this inherently applies align-self: stretch
+  @include border-radius($card-inner-border-radius);
+}
+
+// Card image caps
+.card-img-top {
+  width: 100%; // Required because we use flexbox and this inherently applies align-self: stretch
+  @include border-top-radius($card-inner-border-radius);
+}
+
+.card-img-bottom {
+  width: 100%; // Required because we use flexbox and this inherently applies align-self: stretch
+  @include border-bottom-radius($card-inner-border-radius);
+}
+
+
+// Card deck
+
+.card-deck {
+  display: flex;
+  flex-direction: column;
+
+  .card {
+    margin-bottom: $card-deck-margin;
+  }
+
+  @include media-breakpoint-up(sm) {
+    flex-flow: row wrap;
+    margin-right: -$card-deck-margin;
+    margin-left: -$card-deck-margin;
+
+    .card {
+      display: flex;
+      // Flexbugs #4: https://github.com/philipwalton/flexbugs#flexbug-4
+      flex: 1 0 0%;
+      flex-direction: column;
+      margin-right: $card-deck-margin;
+      margin-bottom: 0; // Override the default
+      margin-left: $card-deck-margin;
+    }
+  }
+}
+
+
+//
+// Card groups
+//
+
+.card-group {
+  display: flex;
+  flex-direction: column;
+
+  // The child selector allows nested `.card` within `.card-group`
+  // to display properly.
+  > .card {
+    margin-bottom: $card-group-margin;
+  }
+
+  @include media-breakpoint-up(sm) {
+    flex-flow: row wrap;
+    // The child selector allows nested `.card` within `.card-group`
+    // to display properly.
+    > .card {
+      // Flexbugs #4: https://github.com/philipwalton/flexbugs#flexbug-4
+      flex: 1 0 0%;
+      margin-bottom: 0;
+
+      + .card {
+        margin-left: 0;
+        border-left: 0;
+      }
+
+      // Handle rounded corners
+      @if $enable-rounded {
+        &:first-child {
+          @include border-right-radius(0);
+
+          .card-img-top,
+          .card-header {
+            border-top-right-radius: 0;
+          }
+          .card-img-bottom,
+          .card-footer {
+            border-bottom-right-radius: 0;
+          }
+        }
+
+        &:last-child {
+          @include border-left-radius(0);
+
+          .card-img-top,
+          .card-header {
+            border-top-left-radius: 0;
+          }
+          .card-img-bottom,
+          .card-footer {
+            border-bottom-left-radius: 0;
+          }
+        }
+
+        &:only-child {
+          @include border-radius($card-border-radius);
+
+          .card-img-top,
+          .card-header {
+            @include border-top-radius($card-border-radius);
+          }
+          .card-img-bottom,
+          .card-footer {
+            @include border-bottom-radius($card-border-radius);
+          }
+        }
+
+        &:not(:first-child):not(:last-child):not(:only-child) {
+          @include border-radius(0);
+
+          .card-img-top,
+          .card-img-bottom,
+          .card-header,
+          .card-footer {
+            @include border-radius(0);
+          }
+        }
+      }
+    }
+  }
+}
+
+
+//
+// Columns
+//
+
+.card-columns {
+  .card {
+    margin-bottom: $card-columns-margin;
+  }
+
+  @include media-breakpoint-up(sm) {
+    column-count: $card-columns-count;
+    column-gap: $card-columns-gap;
+    orphans: 1;
+    widows: 1;
+
+    .card {
+      display: inline-block; // Don't let them vertically span multiple columns
+      width: 100%; // Don't let their width change
+    }
+  }
+}
+
+
+//
+// Accordion
+//
+
+.accordion {
+  .card:not(:first-of-type):not(:last-of-type) {
+    border-bottom: 0;
+    border-radius: 0;
+  }
+
+  .card:not(:first-of-type) {
+    .card-header:first-child {
+      border-radius: 0;
+    }
+  }
+
+  .card:first-of-type {
+    border-bottom: 0;
+    border-bottom-right-radius: 0;
+    border-bottom-left-radius: 0;
+  }
+
+  .card:last-of-type {
+    border-top-left-radius: 0;
+    border-top-right-radius: 0;
+  }
+}
diff --git a/src/sass/bootstrap4/_carousel.scss b/src/sass/bootstrap4/_carousel.scss
new file mode 100644
index 0000000..91c23e5
--- /dev/null
+++ b/src/sass/bootstrap4/_carousel.scss
@@ -0,0 +1,236 @@
+// Notes on the classes:
+//
+// 1. The .carousel-item-left and .carousel-item-right is used to indicate where
+//    the active slide is heading.
+// 2. .active.carousel-item is the current slide.
+// 3. .active.carousel-item-left and .active.carousel-item-right is the current
+//    slide in its in-transition state. Only one of these occurs at a time.
+// 4. .carousel-item-next.carousel-item-left and .carousel-item-prev.carousel-item-right
+//    is the upcoming slide in transition.
+
+.carousel {
+  position: relative;
+}
+
+.carousel-inner {
+  position: relative;
+  width: 100%;
+  overflow: hidden;
+}
+
+.carousel-item {
+  position: relative;
+  display: none;
+  align-items: center;
+  width: 100%;
+  backface-visibility: hidden;
+  perspective: 1000px;
+}
+
+.carousel-item.active,
+.carousel-item-next,
+.carousel-item-prev {
+  display: block;
+  @include transition($carousel-transition);
+}
+
+.carousel-item-next,
+.carousel-item-prev {
+  position: absolute;
+  top: 0;
+}
+
+.carousel-item-next.carousel-item-left,
+.carousel-item-prev.carousel-item-right {
+  transform: translateX(0);
+
+  @supports (transform-style: preserve-3d) {
+    transform: translate3d(0, 0, 0);
+  }
+}
+
+.carousel-item-next,
+.active.carousel-item-right {
+  transform: translateX(100%);
+
+  @supports (transform-style: preserve-3d) {
+    transform: translate3d(100%, 0, 0);
+  }
+}
+
+.carousel-item-prev,
+.active.carousel-item-left {
+  transform: translateX(-100%);
+
+  @supports (transform-style: preserve-3d) {
+    transform: translate3d(-100%, 0, 0);
+  }
+}
+
+
+//
+// Alternate transitions
+//
+
+.carousel-fade {
+  .carousel-item {
+    opacity: 0;
+    transition-duration: .6s;
+    transition-property: opacity;
+  }
+
+  .carousel-item.active,
+  .carousel-item-next.carousel-item-left,
+  .carousel-item-prev.carousel-item-right {
+    opacity: 1;
+  }
+
+  .active.carousel-item-left,
+  .active.carousel-item-right {
+    opacity: 0;
+  }
+
+  .carousel-item-next,
+  .carousel-item-prev,
+  .carousel-item.active,
+  .active.carousel-item-left,
+  .active.carousel-item-prev {
+    transform: translateX(0);
+
+    @supports (transform-style: preserve-3d) {
+      transform: translate3d(0, 0, 0);
+    }
+  }
+}
+
+
+//
+// Left/right controls for nav
+//
+
+.carousel-control-prev,
+.carousel-control-next {
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  // Use flex for alignment (1-3)
+  display: flex; // 1. allow flex styles
+  align-items: center; // 2. vertically center contents
+  justify-content: center; // 3. horizontally center contents
+  width: $carousel-control-width;
+  color: $carousel-control-color;
+  text-align: center;
+  opacity: $carousel-control-opacity;
+  // We can't have a transition here because WebKit cancels the carousel
+  // animation if you trip this while in the middle of another animation.
+
+  // Hover/focus state
+  @include hover-focus {
+    color: $carousel-control-color;
+    text-decoration: none;
+    outline: 0;
+    opacity: .9;
+  }
+}
+.carousel-control-prev {
+  left: 0;
+  @if $enable-gradients {
+    background: linear-gradient(90deg, rgba($black, .25), rgba($black, .001));
+  }
+}
+.carousel-control-next {
+  right: 0;
+  @if $enable-gradients {
+    background: linear-gradient(270deg, rgba($black, .25), rgba($black, .001));
+  }
+}
+
+// Icons for within
+.carousel-control-prev-icon,
+.carousel-control-next-icon {
+  display: inline-block;
+  width: $carousel-control-icon-width;
+  height: $carousel-control-icon-width;
+  background: transparent no-repeat center center;
+  background-size: 100% 100%;
+}
+.carousel-control-prev-icon {
+  background-image: $carousel-control-prev-icon-bg;
+}
+.carousel-control-next-icon {
+  background-image: $carousel-control-next-icon-bg;
+}
+
+
+// Optional indicator pips
+//
+// Add an ordered list with the following class and add a list item for each
+// slide your carousel holds.
+
+.carousel-indicators {
+  position: absolute;
+  right: 0;
+  bottom: 10px;
+  left: 0;
+  z-index: 15;
+  display: flex;
+  justify-content: center;
+  padding-left: 0; // override <ol> default
+  // Use the .carousel-control's width as margin so we don't overlay those
+  margin-right: $carousel-control-width;
+  margin-left: $carousel-control-width;
+  list-style: none;
+
+  li {
+    position: relative;
+    flex: 0 1 auto;
+    width: $carousel-indicator-width;
+    height: $carousel-indicator-height;
+    margin-right: $carousel-indicator-spacer;
+    margin-left: $carousel-indicator-spacer;
+    text-indent: -999px;
+    cursor: pointer;
+    background-color: rgba($carousel-indicator-active-bg, .5);
+
+    // Use pseudo classes to increase the hit area by 10px on top and bottom.
+    &::before {
+      position: absolute;
+      top: -10px;
+      left: 0;
+      display: inline-block;
+      width: 100%;
+      height: 10px;
+      content: "";
+    }
+    &::after {
+      position: absolute;
+      bottom: -10px;
+      left: 0;
+      display: inline-block;
+      width: 100%;
+      height: 10px;
+      content: "";
+    }
+  }
+
+  .active {
+    background-color: $carousel-indicator-active-bg;
+  }
+}
+
+
+// Optional captions
+//
+//
+
+.carousel-caption {
+  position: absolute;
+  right: ((100% - $carousel-caption-width) / 2);
+  bottom: 20px;
+  left: ((100% - $carousel-caption-width) / 2);
+  z-index: 10;
+  padding-top: 20px;
+  padding-bottom: 20px;
+  color: $carousel-caption-color;
+  text-align: center;
+}
diff --git a/src/sass/bootstrap4/_close.scss b/src/sass/bootstrap4/_close.scss
new file mode 100644
index 0000000..a0dd1e2
--- /dev/null
+++ b/src/sass/bootstrap4/_close.scss
@@ -0,0 +1,35 @@
+.close {
+  float: right;
+  font-size: $close-font-size;
+  font-weight: $close-font-weight;
+  line-height: 1;
+  color: $close-color;
+  text-shadow: $close-text-shadow;
+  opacity: .5;
+
+  &:not(:disabled):not(.disabled) {
+
+    @include hover-focus {
+      color: $close-color;
+      text-decoration: none;
+      opacity: .75;
+    }
+
+    // Opinionated: add "hand" cursor to non-disabled .close elements
+    cursor: pointer;
+  }
+}
+
+// Additional properties for button version
+// iOS requires the button element instead of an anchor tag.
+// If you want the anchor version, it requires `href="#"`.
+// See https://developer.mozilla.org/en-US/docs/Web/Events/click#Safari_Mobile
+
+// stylelint-disable property-no-vendor-prefix, selector-no-qualifying-type
+button.close {
+  padding: 0;
+  background-color: transparent;
+  border: 0;
+  -webkit-appearance: none;
+}
+// stylelint-enable
diff --git a/src/sass/bootstrap4/_code.scss b/src/sass/bootstrap4/_code.scss
new file mode 100644
index 0000000..9b2e027
--- /dev/null
+++ b/src/sass/bootstrap4/_code.scss
@@ -0,0 +1,48 @@
+// Inline code
+code {
+  font-size: $code-font-size;
+  color: $code-color;
+  word-break: break-word;
+
+  // Streamline the style when inside anchors to avoid broken underline and more
+  a > & {
+    color: inherit;
+  }
+}
+
+// User input typically entered via keyboard
+kbd {
+  padding: $kbd-padding-y $kbd-padding-x;
+  font-size: $kbd-font-size;
+  color: $kbd-color;
+  background-color: $kbd-bg;
+  @include border-radius($border-radius-sm);
+  @include box-shadow($kbd-box-shadow);
+
+  kbd {
+    padding: 0;
+    font-size: 100%;
+    font-weight: $nested-kbd-font-weight;
+    @include box-shadow(none);
+  }
+}
+
+// Blocks of code
+pre {
+  display: block;
+  font-size: $code-font-size;
+  color: $pre-color;
+
+  // Account for some code outputs that place code tags in pre tags
+  code {
+    font-size: inherit;
+    color: inherit;
+    word-break: normal;
+  }
+}
+
+// Enable scrollable blocks of code
+.pre-scrollable {
+  max-height: $pre-scrollable-max-height;
+  overflow-y: scroll;
+}
diff --git a/src/sass/bootstrap4/_custom-forms.scss b/src/sass/bootstrap4/_custom-forms.scss
new file mode 100644
index 0000000..8348e26
--- /dev/null
+++ b/src/sass/bootstrap4/_custom-forms.scss
@@ -0,0 +1,433 @@
+// Embedded icons from Open Iconic.
+// Released under MIT and copyright 2014 Waybury.
+// https://useiconic.com/open
+
+
+// Checkboxes and radios
+//
+// Base class takes care of all the key behavioral aspects.
+
+.custom-control {
+  position: relative;
+  display: block;
+  min-height: ($font-size-base * $line-height-base);
+  padding-left: $custom-control-gutter;
+}
+
+.custom-control-inline {
+  display: inline-flex;
+  margin-right: $custom-control-spacer-x;
+}
+
+.custom-control-input {
+  position: absolute;
+  z-index: -1; // Put the input behind the label so it doesn't overlay text
+  opacity: 0;
+
+  &:checked ~ .custom-control-label::before {
+    color: $custom-control-indicator-checked-color;
+    @include gradient-bg($custom-control-indicator-checked-bg);
+    @include box-shadow($custom-control-indicator-checked-box-shadow);
+  }
+
+  &:focus ~ .custom-control-label::before {
+    // the mixin is not used here to make sure there is feedback
+    box-shadow: $custom-control-indicator-focus-box-shadow;
+  }
+
+  &:active ~ .custom-control-label::before {
+    color: $custom-control-indicator-active-color;
+    background-color: $custom-control-indicator-active-bg;
+    @include box-shadow($custom-control-indicator-active-box-shadow);
+  }
+
+  &:disabled {
+    ~ .custom-control-label {
+      color: $custom-control-label-disabled-color;
+
+      &::before {
+        background-color: $custom-control-indicator-disabled-bg;
+      }
+    }
+  }
+}
+
+// Custom control indicators
+//
+// Build the custom controls out of pseudo-elements.
+
+.custom-control-label {
+  position: relative;
+  margin-bottom: 0;
+
+  // Background-color and (when enabled) gradient
+  &::before {
+    position: absolute;
+    top: (($font-size-base * $line-height-base - $custom-control-indicator-size) / 2);
+    left: -$custom-control-gutter;
+    display: block;
+    width: $custom-control-indicator-size;
+    height: $custom-control-indicator-size;
+    pointer-events: none;
+    content: "";
+    user-select: none;
+    background-color: $custom-control-indicator-bg;
+    @include box-shadow($custom-control-indicator-box-shadow);
+  }
+
+  // Foreground (icon)
+  &::after {
+    position: absolute;
+    top: (($font-size-base * $line-height-base - $custom-control-indicator-size) / 2);
+    left: -$custom-control-gutter;
+    display: block;
+    width: $custom-control-indicator-size;
+    height: $custom-control-indicator-size;
+    content: "";
+    background-repeat: no-repeat;
+    background-position: center center;
+    background-size: $custom-control-indicator-bg-size;
+  }
+}
+
+
+// Checkboxes
+//
+// Tweak just a few things for checkboxes.
+
+.custom-checkbox {
+  .custom-control-label::before {
+    @include border-radius($custom-checkbox-indicator-border-radius);
+  }
+
+  .custom-control-input:checked ~ .custom-control-label {
+    &::before {
+      @include gradient-bg($custom-control-indicator-checked-bg);
+    }
+    &::after {
+      background-image: $custom-checkbox-indicator-icon-checked;
+    }
+  }
+
+  .custom-control-input:indeterminate ~ .custom-control-label {
+    &::before {
+      @include gradient-bg($custom-checkbox-indicator-indeterminate-bg);
+      @include box-shadow($custom-checkbox-indicator-indeterminate-box-shadow);
+    }
+    &::after {
+      background-image: $custom-checkbox-indicator-icon-indeterminate;
+    }
+  }
+
+  .custom-control-input:disabled {
+    &:checked ~ .custom-control-label::before {
+      background-color: $custom-control-indicator-checked-disabled-bg;
+    }
+    &:indeterminate ~ .custom-control-label::before {
+      background-color: $custom-control-indicator-checked-disabled-bg;
+    }
+  }
+}
+
+// Radios
+//
+// Tweak just a few things for radios.
+
+.custom-radio {
+  .custom-control-label::before {
+    border-radius: $custom-radio-indicator-border-radius;
+  }
+
+  .custom-control-input:checked ~ .custom-control-label {
+    &::before {
+      @include gradient-bg($custom-control-indicator-checked-bg);
+    }
+    &::after {
+      background-image: $custom-radio-indicator-icon-checked;
+    }
+  }
+
+  .custom-control-input:disabled {
+    &:checked ~ .custom-control-label::before {
+      background-color: $custom-control-indicator-checked-disabled-bg;
+    }
+  }
+}
+
+
+// Select
+//
+// Replaces the browser default select with a custom one, mostly pulled from
+// https://primer.github.io/.
+//
+
+.custom-select {
+  display: inline-block;
+  width: 100%;
+  height: $custom-select-height;
+  padding: $custom-select-padding-y ($custom-select-padding-x + $custom-select-indicator-padding) $custom-select-padding-y $custom-select-padding-x;
+  line-height: $custom-select-line-height;
+  color: $custom-select-color;
+  vertical-align: middle;
+  background: $custom-select-bg $custom-select-indicator no-repeat right $custom-select-padding-x center;
+  background-size: $custom-select-bg-size;
+  border: $custom-select-border-width solid $custom-select-border-color;
+  @if $enable-rounded {
+    border-radius: $custom-select-border-radius;
+  } @else {
+    border-radius: 0;
+  }
+  @include box-shadow($custom-select-box-shadow);
+  appearance: none;
+
+  &:focus {
+    border-color: $custom-select-focus-border-color;
+    outline: 0;
+    @if $enable-shadows {
+      box-shadow: $custom-select-box-shadow, $custom-select-focus-box-shadow;
+    } @else {
+      box-shadow: $custom-select-focus-box-shadow;
+    }
+
+    &::-ms-value {
+      // For visual consistency with other platforms/browsers,
+      // suppress the default white text on blue background highlight given to
+      // the selected option text when the (still closed) <select> receives focus
+      // in IE and (under certain conditions) Edge.
+      // See https://github.com/twbs/bootstrap/issues/19398.
+      color: $input-color;
+      background-color: $input-bg;
+    }
+  }
+
+  &[multiple],
+  &[size]:not([size="1"]) {
+    height: auto;
+    padding-right: $custom-select-padding-x;
+    background-image: none;
+  }
+
+  &:disabled {
+    color: $custom-select-disabled-color;
+    background-color: $custom-select-disabled-bg;
+  }
+
+  // Hides the default caret in IE11
+  &::-ms-expand {
+    opacity: 0;
+  }
+}
+
+.custom-select-sm {
+  height: $custom-select-height-sm;
+  padding-top: $custom-select-padding-y;
+  padding-bottom: $custom-select-padding-y;
+  font-size: $custom-select-font-size-sm;
+}
+
+.custom-select-lg {
+  height: $custom-select-height-lg;
+  padding-top: $custom-select-padding-y;
+  padding-bottom: $custom-select-padding-y;
+  font-size: $custom-select-font-size-lg;
+}
+
+
+// File
+//
+// Custom file input.
+
+.custom-file {
+  position: relative;
+  display: inline-block;
+  width: 100%;
+  height: $custom-file-height;
+  margin-bottom: 0;
+}
+
+.custom-file-input {
+  position: relative;
+  z-index: 2;
+  width: 100%;
+  height: $custom-file-height;
+  margin: 0;
+  opacity: 0;
+
+  &:focus ~ .custom-file-label {
+    border-color: $custom-file-focus-border-color;
+    box-shadow: $custom-file-focus-box-shadow;
+
+    &::after {
+      border-color: $custom-file-focus-border-color;
+    }
+  }
+
+  &:disabled ~ .custom-file-label {
+    background-color: $custom-file-disabled-bg;
+  }
+
+  @each $lang, $value in $custom-file-text {
+    &:lang(#{$lang}) ~ .custom-file-label::after {
+      content: $value;
+    }
+  }
+}
+
+.custom-file-label {
+  position: absolute;
+  top: 0;
+  right: 0;
+  left: 0;
+  z-index: 1;
+  height: $custom-file-height;
+  padding: $custom-file-padding-y $custom-file-padding-x;
+  line-height: $custom-file-line-height;
+  color: $custom-file-color;
+  background-color: $custom-file-bg;
+  border: $custom-file-border-width solid $custom-file-border-color;
+  @include border-radius($custom-file-border-radius);
+  @include box-shadow($custom-file-box-shadow);
+
+  &::after {
+    position: absolute;
+    top: 0;
+    right: 0;
+    bottom: 0;
+    z-index: 3;
+    display: block;
+    height: $custom-file-height-inner;
+    padding: $custom-file-padding-y $custom-file-padding-x;
+    line-height: $custom-file-line-height;
+    color: $custom-file-button-color;
+    content: "Browse";
+    @include gradient-bg($custom-file-button-bg);
+    border-left: $custom-file-border-width solid $custom-file-border-color;
+    @include border-radius(0 $custom-file-border-radius $custom-file-border-radius 0);
+  }
+}
+
+// Range
+//
+// Style range inputs the same across browsers. Vendor-specific rules for pseudo
+// elements cannot be mixed. As such, there are no shared styles for focus or
+// active states on prefixed selectors.
+
+.custom-range {
+  width: 100%;
+  padding-left: 0; // Firefox specific
+  background-color: transparent;
+  appearance: none;
+
+  &:focus {
+    outline: none;
+
+    // Pseudo-elements must be split across multiple rulesets to have an affect.
+    // No box-shadow() mixin for focus accessibility.
+    &::-webkit-slider-thumb { box-shadow: $custom-range-thumb-focus-box-shadow; }
+    &::-moz-range-thumb     { box-shadow: $custom-range-thumb-focus-box-shadow; }
+    &::-ms-thumb            { box-shadow: $custom-range-thumb-focus-box-shadow; }
+  }
+
+  &::-moz-focus-outer {
+    border: 0;
+  }
+
+  &::-webkit-slider-thumb {
+    width: $custom-range-thumb-width;
+    height: $custom-range-thumb-height;
+    margin-top: (($custom-range-track-height - $custom-range-thumb-height) / 2); // Webkit specific
+    @include gradient-bg($custom-range-thumb-bg);
+    border: $custom-range-thumb-border;
+    @include border-radius($custom-range-thumb-border-radius);
+    @include box-shadow($custom-range-thumb-box-shadow);
+    @include transition($custom-forms-transition);
+    appearance: none;
+
+    &:active {
+      @include gradient-bg($custom-range-thumb-active-bg);
+    }
+  }
+
+  &::-webkit-slider-runnable-track {
+    width: $custom-range-track-width;
+    height: $custom-range-track-height;
+    color: transparent; // Why?
+    cursor: $custom-range-track-cursor;
+    background-color: $custom-range-track-bg;
+    border-color: transparent;
+    @include border-radius($custom-range-track-border-radius);
+    @include box-shadow($custom-range-track-box-shadow);
+  }
+
+  &::-moz-range-thumb {
+    width: $custom-range-thumb-width;
+    height: $custom-range-thumb-height;
+    @include gradient-bg($custom-range-thumb-bg);
+    border: $custom-range-thumb-border;
+    @include border-radius($custom-range-thumb-border-radius);
+    @include box-shadow($custom-range-thumb-box-shadow);
+    @include transition($custom-forms-transition);
+    appearance: none;
+
+    &:active {
+      @include gradient-bg($custom-range-thumb-active-bg);
+    }
+  }
+
+  &::-moz-range-track {
+    width: $custom-range-track-width;
+    height: $custom-range-track-height;
+    color: transparent;
+    cursor: $custom-range-track-cursor;
+    background-color: $custom-range-track-bg;
+    border-color: transparent; // Firefox specific?
+    @include border-radius($custom-range-track-border-radius);
+    @include box-shadow($custom-range-track-box-shadow);
+  }
+
+  &::-ms-thumb {
+    width: $custom-range-thumb-width;
+    height: $custom-range-thumb-height;
+    margin-top: 0; // Edge specific
+    margin-right: $custom-range-thumb-focus-box-shadow-width; // Workaround that overflowed box-shadow is hidden.
+    margin-left: $custom-range-thumb-focus-box-shadow-width;  // Workaround that overflowed box-shadow is hidden.
+    @include gradient-bg($custom-range-thumb-bg);
+    border: $custom-range-thumb-border;
+    @include border-radius($custom-range-thumb-border-radius);
+    @include box-shadow($custom-range-thumb-box-shadow);
+    @include transition($custom-forms-transition);
+    appearance: none;
+
+    &:active {
+      @include gradient-bg($custom-range-thumb-active-bg);
+    }
+  }
+
+  &::-ms-track {
+    width: $custom-range-track-width;
+    height: $custom-range-track-height;
+    color: transparent;
+    cursor: $custom-range-track-cursor;
+    background-color: transparent;
+    border-color: transparent;
+    border-width: ($custom-range-thumb-height * .5);
+    @include box-shadow($custom-range-track-box-shadow);
+  }
+
+  &::-ms-fill-lower {
+    background-color: $custom-range-track-bg;
+    @include border-radius($custom-range-track-border-radius);
+  }
+
+  &::-ms-fill-upper {
+    margin-right: 15px; // arbitrary?
+    background-color: $custom-range-track-bg;
+    @include border-radius($custom-range-track-border-radius);
+  }
+}
+
+.custom-control-label::before,
+.custom-file-label,
+.custom-select {
+  @include transition($custom-forms-transition);
+}
diff --git a/src/sass/bootstrap4/_dropdown.scss b/src/sass/bootstrap4/_dropdown.scss
new file mode 100644
index 0000000..ee6f658
--- /dev/null
+++ b/src/sass/bootstrap4/_dropdown.scss
@@ -0,0 +1,166 @@
+// The dropdown wrapper (`<div>`)
+.dropup,
+.dropright,
+.dropdown,
+.dropleft {
+  position: relative;
+}
+
+.dropdown-toggle {
+  // Generate the caret automatically
+  @include caret;
+}
+
+// The dropdown menu
+.dropdown-menu {
+  position: absolute;
+  top: 100%;
+  left: 0;
+  z-index: $zindex-dropdown;
+  display: none; // none by default, but block on "open" of the menu
+  float: left;
+  min-width: $dropdown-min-width;
+  padding: $dropdown-padding-y 0;
+  margin: $dropdown-spacer 0 0; // override default ul
+  font-size: $font-size-base; // Redeclare because nesting can cause inheritance issues
+  color: $body-color;
+  text-align: left; // Ensures proper alignment if parent has it changed (e.g., modal footer)
+  list-style: none;
+  background-color: $dropdown-bg;
+  background-clip: padding-box;
+  border: $dropdown-border-width solid $dropdown-border-color;
+  @include border-radius($dropdown-border-radius);
+  @include box-shadow($dropdown-box-shadow);
+}
+
+.dropdown-menu-right {
+  right: 0;
+  left: auto;
+}
+
+// Allow for dropdowns to go bottom up (aka, dropup-menu)
+// Just add .dropup after the standard .dropdown class and you're set.
+.dropup {
+  .dropdown-menu {
+    top: auto;
+    bottom: 100%;
+    margin-top: 0;
+    margin-bottom: $dropdown-spacer;
+  }
+
+  .dropdown-toggle {
+    @include caret(up);
+  }
+}
+
+.dropright {
+  .dropdown-menu {
+    top: 0;
+    right: auto;
+    left: 100%;
+    margin-top: 0;
+    margin-left: $dropdown-spacer;
+  }
+
+  .dropdown-toggle {
+    @include caret(right);
+    &::after {
+      vertical-align: 0;
+    }
+  }
+}
+
+.dropleft {
+  .dropdown-menu {
+    top: 0;
+    right: 100%;
+    left: auto;
+    margin-top: 0;
+    margin-right: $dropdown-spacer;
+  }
+
+  .dropdown-toggle {
+    @include caret(left);
+    &::before {
+      vertical-align: 0;
+    }
+  }
+}
+
+// When enabled Popper.js, reset basic dropdown position
+// stylelint-disable no-duplicate-selectors
+.dropdown-menu {
+  &[x-placement^="top"],
+  &[x-placement^="right"],
+  &[x-placement^="bottom"],
+  &[x-placement^="left"] {
+    right: auto;
+    bottom: auto;
+  }
+}
+// stylelint-enable no-duplicate-selectors
+
+// Dividers (basically an `<hr>`) within the dropdown
+.dropdown-divider {
+  @include nav-divider($dropdown-divider-bg);
+}
+
+// Links, buttons, and more within the dropdown menu
+//
+// `<button>`-specific styles are denoted with `// For <button>s`
+.dropdown-item {
+  display: block;
+  width: 100%; // For `<button>`s
+  padding: $dropdown-item-padding-y $dropdown-item-padding-x;
+  clear: both;
+  font-weight: $font-weight-normal;
+  color: $dropdown-link-color;
+  text-align: inherit; // For `<button>`s
+  white-space: nowrap; // prevent links from randomly breaking onto new lines
+  background-color: transparent; // For `<button>`s
+  border: 0; // For `<button>`s
+
+  @include hover-focus {
+    color: $dropdown-link-hover-color;
+    text-decoration: none;
+    @include gradient-bg($dropdown-link-hover-bg);
+  }
+
+  &.active,
+  &:active {
+    color: $dropdown-link-active-color;
+    text-decoration: none;
+    @include gradient-bg($dropdown-link-active-bg);
+  }
+
+  &.disabled,
+  &:disabled {
+    color: $dropdown-link-disabled-color;
+    background-color: transparent;
+    // Remove CSS gradients if they're enabled
+    @if $enable-gradients {
+      background-image: none;
+    }
+  }
+}
+
+.dropdown-menu.show {
+  display: block;
+}
+
+// Dropdown section headers
+.dropdown-header {
+  display: block;
+  padding: $dropdown-padding-y $dropdown-item-padding-x;
+  margin-bottom: 0; // for use with heading elements
+  font-size: $font-size-sm;
+  color: $dropdown-header-color;
+  white-space: nowrap; // as with > li > a
+}
+
+// Dropdown text
+.dropdown-item-text {
+  display: block;
+  padding: $dropdown-item-padding-y $dropdown-item-padding-x;
+  color: $dropdown-link-color;
+}
diff --git a/src/sass/bootstrap4/_forms.scss b/src/sass/bootstrap4/_forms.scss
new file mode 100644
index 0000000..5530630
--- /dev/null
+++ b/src/sass/bootstrap4/_forms.scss
@@ -0,0 +1,333 @@
+// stylelint-disable selector-no-qualifying-type
+
+//
+// Textual form controls
+//
+
+.form-control {
+  display: block;
+  width: 100%;
+  height: $input-height;
+  padding: $input-padding-y $input-padding-x;
+  font-size: $font-size-base;
+  line-height: $input-line-height;
+  color: $input-color;
+  background-color: $input-bg;
+  background-clip: padding-box;
+  border: $input-border-width solid $input-border-color;
+
+  // Note: This has no effect on <select>s in some browsers, due to the limited stylability of `<select>`s in CSS.
+  @if $enable-rounded {
+    // Manually use the if/else instead of the mixin to account for iOS override
+    border-radius: $input-border-radius;
+  } @else {
+    // Otherwise undo the iOS default
+    border-radius: 0;
+  }
+
+  @include box-shadow($input-box-shadow);
+  @include transition($input-transition);
+
+  // Unstyle the caret on `<select>`s in IE10+.
+  &::-ms-expand {
+    background-color: transparent;
+    border: 0;
+  }
+
+  // Customize the `:focus` state to imitate native WebKit styles.
+  @include form-control-focus();
+
+  // Placeholder
+  &::placeholder {
+    color: $input-placeholder-color;
+    // Override Firefox's unusual default opacity; see https://github.com/twbs/bootstrap/pull/11526.
+    opacity: 1;
+  }
+
+  // Disabled and read-only inputs
+  //
+  // HTML5 says that controls under a fieldset > legend:first-child won't be
+  // disabled if the fieldset is disabled. Due to implementation difficulty, we
+  // don't honor that edge case; we style them as disabled anyway.
+  &:disabled,
+  &[readonly] {
+    background-color: $input-disabled-bg;
+    // iOS fix for unreadable disabled content; see https://github.com/twbs/bootstrap/issues/11655.
+    opacity: 1;
+  }
+}
+
+select.form-control {
+  &:focus::-ms-value {
+    // Suppress the nested default white text on blue background highlight given to
+    // the selected option text when the (still closed) <select> receives focus
+    // in IE and (under certain conditions) Edge, as it looks bad and cannot be made to
+    // match the appearance of the native widget.
+    // See https://github.com/twbs/bootstrap/issues/19398.
+    color: $input-color;
+    background-color: $input-bg;
+  }
+}
+
+// Make file inputs better match text inputs by forcing them to new lines.
+.form-control-file,
+.form-control-range {
+  display: block;
+  width: 100%;
+}
+
+
+//
+// Labels
+//
+
+// For use with horizontal and inline forms, when you need the label (or legend)
+// text to align with the form controls.
+.col-form-label {
+  padding-top: calc(#{$input-padding-y} + #{$input-border-width});
+  padding-bottom: calc(#{$input-padding-y} + #{$input-border-width});
+  margin-bottom: 0; // Override the `<label>/<legend>` default
+  font-size: inherit; // Override the `<legend>` default
+  line-height: $input-line-height;
+}
+
+.col-form-label-lg {
+  padding-top: calc(#{$input-padding-y-lg} + #{$input-border-width});
+  padding-bottom: calc(#{$input-padding-y-lg} + #{$input-border-width});
+  font-size: $font-size-lg;
+  line-height: $input-line-height-lg;
+}
+
+.col-form-label-sm {
+  padding-top: calc(#{$input-padding-y-sm} + #{$input-border-width});
+  padding-bottom: calc(#{$input-padding-y-sm} + #{$input-border-width});
+  font-size: $font-size-sm;
+  line-height: $input-line-height-sm;
+}
+
+
+// Readonly controls as plain text
+//
+// Apply class to a readonly input to make it appear like regular plain
+// text (without any border, background color, focus indicator)
+
+.form-control-plaintext {
+  display: block;
+  width: 100%;
+  padding-top: $input-padding-y;
+  padding-bottom: $input-padding-y;
+  margin-bottom: 0; // match inputs if this class comes on inputs with default margins
+  line-height: $input-line-height;
+  color: $input-plaintext-color;
+  background-color: transparent;
+  border: solid transparent;
+  border-width: $input-border-width 0;
+
+  &.form-control-sm,
+  &.form-control-lg {
+    padding-right: 0;
+    padding-left: 0;
+  }
+}
+
+
+// Form control sizing
+//
+// Build on `.form-control` with modifier classes to decrease or increase the
+// height and font-size of form controls.
+//
+// Repeated in `_input_group.scss` to avoid Sass extend issues.
+
+.form-control-sm {
+  height: $input-height-sm;
+  padding: $input-padding-y-sm $input-padding-x-sm;
+  font-size: $font-size-sm;
+  line-height: $input-line-height-sm;
+  @include border-radius($input-border-radius-sm);
+}
+
+.form-control-lg {
+  height: $input-height-lg;
+  padding: $input-padding-y-lg $input-padding-x-lg;
+  font-size: $font-size-lg;
+  line-height: $input-line-height-lg;
+  @include border-radius($input-border-radius-lg);
+}
+
+// stylelint-disable no-duplicate-selectors
+select.form-control {
+  &[size],
+  &[multiple] {
+    height: auto;
+  }
+}
+
+textarea.form-control {
+  height: auto;
+}
+// stylelint-enable no-duplicate-selectors
+
+// Form groups
+//
+// Designed to help with the organization and spacing of vertical forms. For
+// horizontal forms, use the predefined grid classes.
+
+.form-group {
+  margin-bottom: $form-group-margin-bottom;
+}
+
+.form-text {
+  display: block;
+  margin-top: $form-text-margin-top;
+}
+
+
+// Form grid
+//
+// Special replacement for our grid system's `.row` for tighter form layouts.
+
+.form-row {
+  display: flex;
+  flex-wrap: wrap;
+  margin-right: -5px;
+  margin-left: -5px;
+
+  > .col,
+  > [class*="col-"] {
+    padding-right: 5px;
+    padding-left: 5px;
+  }
+}
+
+
+// Checkboxes and radios
+//
+// Indent the labels to position radios/checkboxes as hanging controls.
+
+.form-check {
+  position: relative;
+  display: block;
+  padding-left: $form-check-input-gutter;
+}
+
+.form-check-input {
+  position: absolute;
+  margin-top: $form-check-input-margin-y;
+  margin-left: -$form-check-input-gutter;
+
+  &:disabled ~ .form-check-label {
+    color: $text-muted;
+  }
+}
+
+.form-check-label {
+  margin-bottom: 0; // Override default `<label>` bottom margin
+}
+
+.form-check-inline {
+  display: inline-flex;
+  align-items: center;
+  padding-left: 0; // Override base .form-check
+  margin-right: $form-check-inline-margin-x;
+
+  // Undo .form-check-input defaults and add some `margin-right`.
+  .form-check-input {
+    position: static;
+    margin-top: 0;
+    margin-right: $form-check-inline-input-margin-x;
+    margin-left: 0;
+  }
+}
+
+
+// Form validation
+//
+// Provide feedback to users when form field values are valid or invalid. Works
+// primarily for client-side validation via scoped `:invalid` and `:valid`
+// pseudo-classes but also includes `.is-invalid` and `.is-valid` classes for
+// server side validation.
+
+@include form-validation-state("valid", $form-feedback-valid-color);
+@include form-validation-state("invalid", $form-feedback-invalid-color);
+
+// Inline forms
+//
+// Make forms appear inline(-block) by adding the `.form-inline` class. Inline
+// forms begin stacked on extra small (mobile) devices and then go inline when
+// viewports reach <768px.
+//
+// Requires wrapping inputs and labels with `.form-group` for proper display of
+// default HTML form controls and our custom form controls (e.g., input groups).
+
+.form-inline {
+  display: flex;
+  flex-flow: row wrap;
+  align-items: center; // Prevent shorter elements from growing to same height as others (e.g., small buttons growing to normal sized button height)
+
+  // Because we use flex, the initial sizing of checkboxes is collapsed and
+  // doesn't occupy the full-width (which is what we want for xs grid tier),
+  // so we force that here.
+  .form-check {
+    width: 100%;
+  }
+
+  // Kick in the inline
+  @include media-breakpoint-up(sm) {
+    label {
+      display: flex;
+      align-items: center;
+      justify-content: center;
+      margin-bottom: 0;
+    }
+
+    // Inline-block all the things for "inline"
+    .form-group {
+      display: flex;
+      flex: 0 0 auto;
+      flex-flow: row wrap;
+      align-items: center;
+      margin-bottom: 0;
+    }
+
+    // Allow folks to *not* use `.form-group`
+    .form-control {
+      display: inline-block;
+      width: auto; // Prevent labels from stacking above inputs in `.form-group`
+      vertical-align: middle;
+    }
+
+    // Make static controls behave like regular ones
+    .form-control-plaintext {
+      display: inline-block;
+    }
+
+    .input-group,
+    .custom-select {
+      width: auto;
+    }
+
+    // Remove default margin on radios/checkboxes that were used for stacking, and
+    // then undo the floating of radios and checkboxes to match.
+    .form-check {
+      display: flex;
+      align-items: center;
+      justify-content: center;
+      width: auto;
+      padding-left: 0;
+    }
+    .form-check-input {
+      position: relative;
+      margin-top: 0;
+      margin-right: $form-check-input-margin-x;
+      margin-left: 0;
+    }
+
+    .custom-control {
+      align-items: center;
+      justify-content: center;
+    }
+    .custom-control-label {
+      margin-bottom: 0;
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/_functions.scss b/src/sass/bootstrap4/_functions.scss
new file mode 100644
index 0000000..bf8be9a
--- /dev/null
+++ b/src/sass/bootstrap4/_functions.scss
@@ -0,0 +1,86 @@
+// Bootstrap functions
+//
+// Utility mixins and functions for evaluating source code across our variables, maps, and mixins.
+
+// Ascending
+// Used to evaluate Sass maps like our grid breakpoints.
+@mixin _assert-ascending($map, $map-name) {
+  $prev-key: null;
+  $prev-num: null;
+  @each $key, $num in $map {
+    @if $prev-num == null {
+      // Do nothing
+    } @else if not comparable($prev-num, $num) {
+      @warn "Potentially invalid value for #{$map-name}: This map must be in ascending order, but key '#{$key}' has value #{$num} whose unit makes it incomparable to #{$prev-num}, the value of the previous key '#{$prev-key}' !";
+    } @else if $prev-num >= $num {
+      @warn "Invalid value for #{$map-name}: This map must be in ascending order, but key '#{$key}' has value #{$num} which isn't greater than #{$prev-num}, the value of the previous key '#{$prev-key}' !";
+    }
+    $prev-key: $key;
+    $prev-num: $num;
+  }
+}
+
+// Starts at zero
+// Another grid mixin that ensures the min-width of the lowest breakpoint starts at 0.
+@mixin _assert-starts-at-zero($map) {
+  $values: map-values($map);
+  $first-value: nth($values, 1);
+  @if $first-value != 0 {
+    @warn "First breakpoint in `$grid-breakpoints` must start at 0, but starts at #{$first-value}.";
+  }
+}
+
+// Replace `$search` with `$replace` in `$string`
+// Used on our SVG icon backgrounds for custom forms.
+//
+// @author Hugo Giraudel
+// @param {String} $string - Initial string
+// @param {String} $search - Substring to replace
+// @param {String} $replace ('') - New value
+// @return {String} - Updated string
+@function str-replace($string, $search, $replace: "") {
+  $index: str-index($string, $search);
+
+  @if $index {
+    @return str-slice($string, 1, $index - 1) + $replace + str-replace(str-slice($string, $index + str-length($search)), $search, $replace);
+  }
+
+  @return $string;
+}
+
+// Color contrast
+@function color-yiq($color) {
+  $r: red($color);
+  $g: green($color);
+  $b: blue($color);
+
+  $yiq: (($r * 299) + ($g * 587) + ($b * 114)) / 1000;
+
+  @if ($yiq >= $yiq-contrasted-threshold) {
+    @return $yiq-text-dark;
+  } @else {
+    @return $yiq-text-light;
+  }
+}
+
+// Retrieve color Sass maps
+@function color($key: "blue") {
+  @return map-get($colors, $key);
+}
+
+@function theme-color($key: "primary") {
+  @return map-get($theme-colors, $key);
+}
+
+@function gray($key: "100") {
+  @return map-get($grays, $key);
+}
+
+// Request a theme color level
+@function theme-color-level($color-name: "primary", $level: 0) {
+  $color: theme-color($color-name);
+  $color-base: if($level > 0, $black, $white);
+  $level: abs($level);
+
+  @return mix($color-base, $color, $level * $theme-color-interval);
+}
diff --git a/src/sass/bootstrap4/_grid.scss b/src/sass/bootstrap4/_grid.scss
new file mode 100644
index 0000000..a227515
--- /dev/null
+++ b/src/sass/bootstrap4/_grid.scss
@@ -0,0 +1,52 @@
+// Container widths
+//
+// Set the container width, and override it for fixed navbars in media queries.
+
+@if $enable-grid-classes {
+  .container {
+    @include make-container();
+    @include make-container-max-widths();
+  }
+}
+
+// Fluid container
+//
+// Utilizes the mixin meant for fixed width containers, but with 100% width for
+// fluid, full width layouts.
+
+@if $enable-grid-classes {
+  .container-fluid {
+    @include make-container();
+  }
+}
+
+// Row
+//
+// Rows contain and clear the floats of your columns.
+
+@if $enable-grid-classes {
+  .row {
+    @include make-row();
+  }
+
+  // Remove the negative margin from default .row, then the horizontal padding
+  // from all immediate children columns (to prevent runaway style inheritance).
+  .no-gutters {
+    margin-right: 0;
+    margin-left: 0;
+
+    > .col,
+    > [class*="col-"] {
+      padding-right: 0;
+      padding-left: 0;
+    }
+  }
+}
+
+// Columns
+//
+// Common styles for small and large grid columns
+
+@if $enable-grid-classes {
+  @include make-grid-columns();
+}
diff --git a/src/sass/bootstrap4/_images.scss b/src/sass/bootstrap4/_images.scss
new file mode 100644
index 0000000..2bce02f
--- /dev/null
+++ b/src/sass/bootstrap4/_images.scss
@@ -0,0 +1,42 @@
+// Responsive images (ensure images don't scale beyond their parents)
+//
+// This is purposefully opt-in via an explicit class rather than being the default for all `<img>`s.
+// We previously tried the "images are responsive by default" approach in Bootstrap v2,
+// and abandoned it in Bootstrap v3 because it breaks lots of third-party widgets (including Google Maps)
+// which weren't expecting the images within themselves to be involuntarily resized.
+// See also https://github.com/twbs/bootstrap/issues/18178
+.img-fluid {
+  @include img-fluid;
+}
+
+
+// Image thumbnails
+.img-thumbnail {
+  padding: $thumbnail-padding;
+  background-color: $thumbnail-bg;
+  border: $thumbnail-border-width solid $thumbnail-border-color;
+  @include border-radius($thumbnail-border-radius);
+  @include box-shadow($thumbnail-box-shadow);
+
+  // Keep them at most 100% wide
+  @include img-fluid;
+}
+
+//
+// Figures
+//
+
+.figure {
+  // Ensures the caption's text aligns with the image.
+  display: inline-block;
+}
+
+.figure-img {
+  margin-bottom: ($spacer / 2);
+  line-height: 1;
+}
+
+.figure-caption {
+  font-size: $figure-caption-font-size;
+  color: $figure-caption-color;
+}
diff --git a/src/sass/bootstrap4/_input-group.scss b/src/sass/bootstrap4/_input-group.scss
new file mode 100644
index 0000000..2ed5f33
--- /dev/null
+++ b/src/sass/bootstrap4/_input-group.scss
@@ -0,0 +1,173 @@
+// stylelint-disable selector-no-qualifying-type
+
+//
+// Base styles
+//
+
+.input-group {
+  position: relative;
+  display: flex;
+  flex-wrap: wrap; // For form validation feedback
+  align-items: stretch;
+  width: 100%;
+
+  > .form-control,
+  > .custom-select,
+  > .custom-file {
+    position: relative; // For focus state's z-index
+    flex: 1 1 auto;
+    // Add width 1% and flex-basis auto to ensure that button will not wrap out
+    // the column. Applies to IE Edge+ and Firefox. Chrome does not require this.
+    width: 1%;
+    margin-bottom: 0;
+
+    + .form-control,
+    + .custom-select,
+    + .custom-file {
+      margin-left: -$input-border-width;
+    }
+  }
+
+  // Bring the "active" form control to the top of surrounding elements
+  > .form-control:focus,
+  > .custom-select:focus,
+  > .custom-file .custom-file-input:focus ~ .custom-file-label {
+    z-index: 3;
+  }
+
+  // Bring the custom file input above the label
+  > .custom-file .custom-file-input:focus {
+    z-index: 4;
+  }
+
+  > .form-control,
+  > .custom-select {
+    &:not(:last-child) { @include border-right-radius(0); }
+    &:not(:first-child) { @include border-left-radius(0); }
+  }
+
+  // Custom file inputs have more complex markup, thus requiring different
+  // border-radius overrides.
+  > .custom-file {
+    display: flex;
+    align-items: center;
+
+    &:not(:last-child) .custom-file-label,
+    &:not(:last-child) .custom-file-label::after { @include border-right-radius(0); }
+    &:not(:first-child) .custom-file-label { @include border-left-radius(0); }
+  }
+}
+
+
+// Prepend and append
+//
+// While it requires one extra layer of HTML for each, dedicated prepend and
+// append elements allow us to 1) be less clever, 2) simplify our selectors, and
+// 3) support HTML5 form validation.
+
+.input-group-prepend,
+.input-group-append {
+  display: flex;
+
+  // Ensure buttons are always above inputs for more visually pleasing borders.
+  // This isn't needed for `.input-group-text` since it shares the same border-color
+  // as our inputs.
+  .btn {
+    position: relative;
+    z-index: 2;
+  }
+
+  .btn + .btn,
+  .btn + .input-group-text,
+  .input-group-text + .input-group-text,
+  .input-group-text + .btn {
+    margin-left: -$input-border-width;
+  }
+}
+
+.input-group-prepend { margin-right: -$input-border-width; }
+.input-group-append { margin-left: -$input-border-width; }
+
+
+// Textual addons
+//
+// Serves as a catch-all element for any text or radio/checkbox input you wish
+// to prepend or append to an input.
+
+.input-group-text {
+  display: flex;
+  align-items: center;
+  padding: $input-padding-y $input-padding-x;
+  margin-bottom: 0; // Allow use of <label> elements by overriding our default margin-bottom
+  font-size: $font-size-base; // Match inputs
+  font-weight: $font-weight-normal;
+  line-height: $input-line-height;
+  color: $input-group-addon-color;
+  text-align: center;
+  white-space: nowrap;
+  background-color: $input-group-addon-bg;
+  border: $input-border-width solid $input-group-addon-border-color;
+  @include border-radius($input-border-radius);
+
+  // Nuke default margins from checkboxes and radios to vertically center within.
+  input[type="radio"],
+  input[type="checkbox"] {
+    margin-top: 0;
+  }
+}
+
+
+// Sizing
+//
+// Remix the default form control sizing classes into new ones for easier
+// manipulation.
+
+.input-group-lg > .form-control,
+.input-group-lg > .input-group-prepend > .input-group-text,
+.input-group-lg > .input-group-append > .input-group-text,
+.input-group-lg > .input-group-prepend > .btn,
+.input-group-lg > .input-group-append > .btn {
+  height: $input-height-lg;
+  padding: $input-padding-y-lg $input-padding-x-lg;
+  font-size: $font-size-lg;
+  line-height: $input-line-height-lg;
+  @include border-radius($input-border-radius-lg);
+}
+
+.input-group-sm > .form-control,
+.input-group-sm > .input-group-prepend > .input-group-text,
+.input-group-sm > .input-group-append > .input-group-text,
+.input-group-sm > .input-group-prepend > .btn,
+.input-group-sm > .input-group-append > .btn {
+  height: $input-height-sm;
+  padding: $input-padding-y-sm $input-padding-x-sm;
+  font-size: $font-size-sm;
+  line-height: $input-line-height-sm;
+  @include border-radius($input-border-radius-sm);
+}
+
+
+// Prepend and append rounded corners
+//
+// These rulesets must come after the sizing ones to properly override sm and lg
+// border-radius values when extending. They're more specific than we'd like
+// with the `.input-group >` part, but without it, we cannot override the sizing.
+
+
+.input-group > .input-group-prepend > .btn,
+.input-group > .input-group-prepend > .input-group-text,
+.input-group > .input-group-append:not(:last-child) > .btn,
+.input-group > .input-group-append:not(:last-child) > .input-group-text,
+.input-group > .input-group-append:last-child > .btn:not(:last-child):not(.dropdown-toggle),
+.input-group > .input-group-append:last-child > .input-group-text:not(:last-child) {
+  @include border-right-radius(0);
+}
+
+.input-group > .input-group-append > .btn,
+.input-group > .input-group-append > .input-group-text,
+.input-group > .input-group-prepend:not(:first-child) > .btn,
+.input-group > .input-group-prepend:not(:first-child) > .input-group-text,
+.input-group > .input-group-prepend:first-child > .btn:not(:first-child),
+.input-group > .input-group-prepend:first-child > .input-group-text:not(:first-child) {
+  @include border-left-radius(0);
+}
diff --git a/src/sass/bootstrap4/_jumbotron.scss b/src/sass/bootstrap4/_jumbotron.scss
new file mode 100644
index 0000000..7966bba
--- /dev/null
+++ b/src/sass/bootstrap4/_jumbotron.scss
@@ -0,0 +1,16 @@
+.jumbotron {
+  padding: $jumbotron-padding ($jumbotron-padding / 2);
+  margin-bottom: $jumbotron-padding;
+  background-color: $jumbotron-bg;
+  @include border-radius($border-radius-lg);
+
+  @include media-breakpoint-up(sm) {
+    padding: ($jumbotron-padding * 2) $jumbotron-padding;
+  }
+}
+
+.jumbotron-fluid {
+  padding-right: 0;
+  padding-left: 0;
+  @include border-radius(0);
+}
diff --git a/src/sass/bootstrap4/_list-group.scss b/src/sass/bootstrap4/_list-group.scss
new file mode 100644
index 0000000..9f145c1
--- /dev/null
+++ b/src/sass/bootstrap4/_list-group.scss
@@ -0,0 +1,115 @@
+// Base class
+//
+// Easily usable on <ul>, <ol>, or <div>.
+
+.list-group {
+  display: flex;
+  flex-direction: column;
+
+  // No need to set list-style: none; since .list-group-item is block level
+  padding-left: 0; // reset padding because ul and ol
+  margin-bottom: 0;
+}
+
+
+// Interactive list items
+//
+// Use anchor or button elements instead of `li`s or `div`s to create interactive
+// list items. Includes an extra `.active` modifier class for selected items.
+
+.list-group-item-action {
+  width: 100%; // For `<button>`s (anchors become 100% by default though)
+  color: $list-group-action-color;
+  text-align: inherit; // For `<button>`s (anchors inherit)
+
+  // Hover state
+  @include hover-focus {
+    color: $list-group-action-hover-color;
+    text-decoration: none;
+    background-color: $list-group-hover-bg;
+  }
+
+  &:active {
+    color: $list-group-action-active-color;
+    background-color: $list-group-action-active-bg;
+  }
+}
+
+
+// Individual list items
+//
+// Use on `li`s or `div`s within the `.list-group` parent.
+
+.list-group-item {
+  position: relative;
+  display: block;
+  padding: $list-group-item-padding-y $list-group-item-padding-x;
+  // Place the border on the list items and negative margin up for better styling
+  margin-bottom: -$list-group-border-width;
+  background-color: $list-group-bg;
+  border: $list-group-border-width solid $list-group-border-color;
+
+  &:first-child {
+    @include border-top-radius($list-group-border-radius);
+  }
+
+  &:last-child {
+    margin-bottom: 0;
+    @include border-bottom-radius($list-group-border-radius);
+  }
+
+  @include hover-focus {
+    z-index: 1; // Place hover/active items above their siblings for proper border styling
+    text-decoration: none;
+  }
+
+  &.disabled,
+  &:disabled {
+    color: $list-group-disabled-color;
+    background-color: $list-group-disabled-bg;
+  }
+
+  // Include both here for `<a>`s and `<button>`s
+  &.active {
+    z-index: 2; // Place active items above their siblings for proper border styling
+    color: $list-group-active-color;
+    background-color: $list-group-active-bg;
+    border-color: $list-group-active-border-color;
+  }
+}
+
+
+// Flush list items
+//
+// Remove borders and border-radius to keep list group items edge-to-edge. Most
+// useful within other components (e.g., cards).
+
+.list-group-flush {
+  .list-group-item {
+    border-right: 0;
+    border-left: 0;
+    @include border-radius(0);
+  }
+
+  &:first-child {
+    .list-group-item:first-child {
+      border-top: 0;
+    }
+  }
+
+  &:last-child {
+    .list-group-item:last-child {
+      border-bottom: 0;
+    }
+  }
+}
+
+
+// Contextual variants
+//
+// Add modifier classes to change text and background color on individual items.
+// Organizationally, this must come after the `:hover` states.
+
+@each $color, $value in $theme-colors {
+  @include list-group-item-variant($color, theme-color-level($color, -9), theme-color-level($color, 6));
+}
diff --git a/src/sass/bootstrap4/_media.scss b/src/sass/bootstrap4/_media.scss
new file mode 100644
index 0000000..b573052
--- /dev/null
+++ b/src/sass/bootstrap4/_media.scss
@@ -0,0 +1,8 @@
+.media {
+  display: flex;
+  align-items: flex-start;
+}
+
+.media-body {
+  flex: 1;
+}
diff --git a/src/sass/bootstrap4/_mixins.scss b/src/sass/bootstrap4/_mixins.scss
new file mode 100644
index 0000000..8710166
--- /dev/null
+++ b/src/sass/bootstrap4/_mixins.scss
@@ -0,0 +1,41 @@
+// Toggles
+//
+// Used in conjunction with global variables to enable certain theme features.
+
+// Utilities
+@import "mixins/breakpoints";
+@import "mixins/hover";
+@import "mixins/image";
+@import "mixins/badge";
+@import "mixins/resize";
+@import "mixins/screen-reader";
+@import "mixins/size";
+@import "mixins/reset-text";
+@import "mixins/text-emphasis";
+@import "mixins/text-hide";
+@import "mixins/text-truncate";
+@import "mixins/visibility";
+
+// // Components
+@import "mixins/alert";
+@import "mixins/buttons";
+@import "mixins/caret";
+@import "mixins/pagination";
+@import "mixins/lists";
+@import "mixins/list-group";
+@import "mixins/nav-divider";
+@import "mixins/forms";
+@import "mixins/table-row";
+
+// // Skins
+@import "mixins/background-variant";
+@import "mixins/border-radius";
+@import "mixins/box-shadow";
+@import "mixins/gradients";
+@import "mixins/transition";
+
+// // Layout
+@import "mixins/clearfix";
+@import "mixins/grid-framework";
+@import "mixins/grid";
+@import "mixins/float";
diff --git a/src/sass/bootstrap4/_modal.scss b/src/sass/bootstrap4/_modal.scss
new file mode 100644
index 0000000..f20bb9d
--- /dev/null
+++ b/src/sass/bootstrap4/_modal.scss
@@ -0,0 +1,180 @@
+// .modal-open      - body class for killing the scroll
+// .modal           - container to scroll within
+// .modal-dialog    - positioning shell for the actual modal
+// .modal-content   - actual modal w/ bg and corners and stuff
+
+
+.modal-open {
+  // Kill the scroll on the body
+  overflow: hidden;
+
+  .modal {
+    overflow-x: hidden;
+    overflow-y: auto;
+  }
+}
+
+// Container that the modal scrolls within
+.modal {
+  position: fixed;
+  top: 0;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  z-index: $zindex-modal;
+  display: none;
+  overflow: hidden;
+  // Prevent Chrome on Windows from adding a focus outline. For details, see
+  // https://github.com/twbs/bootstrap/pull/10951.
+  outline: 0;
+  // We deliberately don't use `-webkit-overflow-scrolling: touch;` due to a
+  // gnarly iOS Safari bug: https://bugs.webkit.org/show_bug.cgi?id=158342
+  // See also https://github.com/twbs/bootstrap/issues/17695
+}
+
+// Shell div to position the modal with bottom padding
+.modal-dialog {
+  position: relative;
+  width: auto;
+  margin: $modal-dialog-margin;
+  // allow clicks to pass through for custom click handling to close modal
+  pointer-events: none;
+
+  // When fading in the modal, animate it to slide down
+  .modal.fade & {
+    @include transition($modal-transition);
+    transform: translate(0, -25%);
+  }
+  .modal.show & {
+    transform: translate(0, 0);
+  }
+}
+
+.modal-dialog-centered {
+  display: flex;
+  align-items: center;
+  min-height: calc(100% - (#{$modal-dialog-margin} * 2));
+
+  // Ensure `modal-dialog-centered` extends the full height of the view (IE10/11)
+  &::before {
+    display: block; // IE10
+    height: calc(100vh - (#{$modal-dialog-margin} * 2));
+    content: "";
+  }
+}
+
+// Actual modal
+.modal-content {
+  position: relative;
+  display: flex;
+  flex-direction: column;
+  width: 100%; // Ensure `.modal-content` extends the full width of the parent `.modal-dialog`
+  // counteract the pointer-events: none; in the .modal-dialog
+  pointer-events: auto;
+  background-color: $modal-content-bg;
+  background-clip: padding-box;
+  border: $modal-content-border-width solid $modal-content-border-color;
+  @include border-radius($modal-content-border-radius);
+  @include box-shadow($modal-content-box-shadow-xs);
+  // Remove focus outline from opened modal
+  outline: 0;
+}
+
+// Modal background
+.modal-backdrop {
+  position: fixed;
+  top: 0;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  z-index: $zindex-modal-backdrop;
+  background-color: $modal-backdrop-bg;
+
+  // Fade for backdrop
+  &.fade { opacity: 0; }
+  &.show { opacity: $modal-backdrop-opacity; }
+}
+
+// Modal header
+// Top section of the modal w/ title and dismiss
+.modal-header {
+  display: flex;
+  align-items: flex-start; // so the close btn always stays on the upper right corner
+  justify-content: space-between; // Put modal header elements (title and dismiss) on opposite ends
+  padding: $modal-header-padding;
+  border-bottom: $modal-header-border-width solid $modal-header-border-color;
+  @include border-top-radius($modal-content-border-radius);
+
+  .close {
+    padding: $modal-header-padding;
+    // auto on the left force icon to the right even when there is no .modal-title
+    margin: (-$modal-header-padding) (-$modal-header-padding) (-$modal-header-padding) auto;
+  }
+}
+
+// Title text within header
+.modal-title {
+  margin-bottom: 0;
+  line-height: $modal-title-line-height;
+}
+
+// Modal body
+// Where all modal content resides (sibling of .modal-header and .modal-footer)
+.modal-body {
+  position: relative;
+  // Enable `flex-grow: 1` so that the body take up as much space as possible
+  // when should there be a fixed height on `.modal-dialog`.
+  flex: 1 1 auto;
+  padding: $modal-inner-padding;
+}
+
+// Footer (for actions)
+.modal-footer {
+  display: flex;
+  align-items: center; // vertically center
+  justify-content: flex-end; // Right align buttons with flex property because text-align doesn't work on flex items
+  padding: $modal-inner-padding;
+  border-top: $modal-footer-border-width solid $modal-footer-border-color;
+
+  // Easily place margin between footer elements
+  > :not(:first-child) { margin-left: .25rem; }
+  > :not(:last-child) { margin-right: .25rem; }
+}
+
+// Measure scrollbar width for padding body during modal show/hide
+.modal-scrollbar-measure {
+  position: absolute;
+  top: -9999px;
+  width: 50px;
+  height: 50px;
+  overflow: scroll;
+}
+
+// Scale up the modal
+@include media-breakpoint-up(sm) {
+  // Automatically set modal's width for larger viewports
+  .modal-dialog {
+    max-width: $modal-md;
+    margin: $modal-dialog-margin-y-sm-up auto;
+  }
+
+  .modal-dialog-centered {
+    min-height: calc(100% - (#{$modal-dialog-margin-y-sm-up} * 2));
+
+    &::before {
+      height: calc(100vh - (#{$modal-dialog-margin-y-sm-up} * 2));
+    }
+
+  }
+
+  .modal-content {
+    @include box-shadow($modal-content-box-shadow-sm-up);
+  }
+
+  .modal-sm { max-width: $modal-sm; }
+
+}
+
+@include media-breakpoint-up(lg) {
+  .modal-lg { max-width: $modal-lg; }
+}
diff --git a/src/sass/bootstrap4/_nav.scss b/src/sass/bootstrap4/_nav.scss
new file mode 100644
index 0000000..fc82161
--- /dev/null
+++ b/src/sass/bootstrap4/_nav.scss
@@ -0,0 +1,118 @@
+// Base class
+//
+// Kickstart any navigation component with a set of style resets. Works with
+// `<nav>`s or `<ul>`s.
+
+.nav {
+  display: flex;
+  flex-wrap: wrap;
+  padding-left: 0;
+  margin-bottom: 0;
+  list-style: none;
+}
+
+.nav-link {
+  display: block;
+  padding: $nav-link-padding-y $nav-link-padding-x;
+
+  @include hover-focus {
+    text-decoration: none;
+  }
+
+  // Disabled state lightens text
+  &.disabled {
+    color: $nav-link-disabled-color;
+  }
+}
+
+//
+// Tabs
+//
+
+.nav-tabs {
+  border-bottom: $nav-tabs-border-width solid $nav-tabs-border-color;
+
+  .nav-item {
+    margin-bottom: -$nav-tabs-border-width;
+  }
+
+  .nav-link {
+    border: $nav-tabs-border-width solid transparent;
+    @include border-top-radius($nav-tabs-border-radius);
+
+    @include hover-focus {
+      border-color: $nav-tabs-link-hover-border-color;
+    }
+
+    &.disabled {
+      color: $nav-link-disabled-color;
+      background-color: transparent;
+      border-color: transparent;
+    }
+  }
+
+  .nav-link.active,
+  .nav-item.show .nav-link {
+    color: $nav-tabs-link-active-color;
+    background-color: $nav-tabs-link-active-bg;
+    border-color: $nav-tabs-link-active-border-color;
+  }
+
+  .dropdown-menu {
+    // Make dropdown border overlap tab border
+    margin-top: -$nav-tabs-border-width;
+    // Remove the top rounded corners here since there is a hard edge above the menu
+    @include border-top-radius(0);
+  }
+}
+
+
+//
+// Pills
+//
+
+.nav-pills {
+  .nav-link {
+    @include border-radius($nav-pills-border-radius);
+  }
+
+  .nav-link.active,
+  .show > .nav-link {
+    color: $nav-pills-link-active-color;
+    background-color: $nav-pills-link-active-bg;
+  }
+}
+
+
+//
+// Justified variants
+//
+
+.nav-fill {
+  .nav-item {
+    flex: 1 1 auto;
+    text-align: center;
+  }
+}
+
+.nav-justified {
+  .nav-item {
+    flex-basis: 0;
+    flex-grow: 1;
+    text-align: center;
+  }
+}
+
+
+// Tabbable tabs
+//
+// Hide tabbable panes to start, show them when `.active`
+
+.tab-content {
+  > .tab-pane {
+    display: none;
+  }
+  > .active {
+    display: block;
+  }
+}
diff --git a/src/sass/bootstrap4/_navbar.scss b/src/sass/bootstrap4/_navbar.scss
new file mode 100644
index 0000000..52de505
--- /dev/null
+++ b/src/sass/bootstrap4/_navbar.scss
@@ -0,0 +1,299 @@
+// Contents
+//
+// Navbar
+// Navbar brand
+// Navbar nav
+// Navbar text
+// Navbar divider
+// Responsive navbar
+// Navbar position
+// Navbar themes
+
+
+// Navbar
+//
+// Provide a static navbar from which we expand to create full-width, fixed, and
+// other navbar variations.
+
+.navbar {
+  position: relative;
+  display: flex;
+  flex-wrap: wrap; // allow us to do the line break for collapsing content
+  align-items: center;
+  justify-content: space-between; // space out brand from logo
+  padding: $navbar-padding-y $navbar-padding-x;
+
+  // Because flex properties aren't inherited, we need to redeclare these first
+  // few properties so that content nested within behave properly.
+  > .container,
+  > .container-fluid {
+    display: flex;
+    flex-wrap: wrap;
+    align-items: center;
+    justify-content: space-between;
+  }
+}
+
+
+// Navbar brand
+//
+// Used for brand, project, or site names.
+
+.navbar-brand {
+  display: inline-block;
+  padding-top: $navbar-brand-padding-y;
+  padding-bottom: $navbar-brand-padding-y;
+  margin-right: $navbar-padding-x;
+  font-size: $navbar-brand-font-size;
+  line-height: inherit;
+  white-space: nowrap;
+
+  @include hover-focus {
+    text-decoration: none;
+  }
+}
+
+
+// Navbar nav
+//
+// Custom navbar navigation (doesn't require `.nav`, but does make use of `.nav-link`).
+
+.navbar-nav {
+  display: flex;
+  flex-direction: column; // cannot use `inherit` to get the `.navbar`s value
+  padding-left: 0;
+  margin-bottom: 0;
+  list-style: none;
+
+  .nav-link {
+    padding-right: 0;
+    padding-left: 0;
+  }
+
+  .dropdown-menu {
+    position: static;
+    float: none;
+  }
+}
+
+
+// Navbar text
+//
+//
+
+.navbar-text {
+  display: inline-block;
+  padding-top: $nav-link-padding-y;
+  padding-bottom: $nav-link-padding-y;
+}
+
+
+// Responsive navbar
+//
+// Custom styles for responsive collapsing and toggling of navbar contents.
+// Powered by the collapse Bootstrap JavaScript plugin.
+
+// When collapsed, prevent the toggleable navbar contents from appearing in
+// the default flexbox row orientation. Requires the use of `flex-wrap: wrap`
+// on the `.navbar` parent.
+.navbar-collapse {
+  flex-basis: 100%;
+  flex-grow: 1;
+  // For always expanded or extra full navbars, ensure content aligns itself
+  // properly vertically. Can be easily overridden with flex utilities.
+  align-items: center;
+}
+
+// Button for toggling the navbar when in its collapsed state
+.navbar-toggler {
+  padding: $navbar-toggler-padding-y $navbar-toggler-padding-x;
+  font-size: $navbar-toggler-font-size;
+  line-height: 1;
+  background-color: transparent; // remove default button style
+  border: $border-width solid transparent; // remove default button style
+  @include border-radius($navbar-toggler-border-radius);
+
+  @include hover-focus {
+    text-decoration: none;
+  }
+
+  // Opinionated: add "hand" cursor to non-disabled .navbar-toggler elements
+  &:not(:disabled):not(.disabled) {
+    cursor: pointer;
+  }
+}
+
+// Keep as a separate element so folks can easily override it with another icon
+// or image file as needed.
+.navbar-toggler-icon {
+  display: inline-block;
+  width: 1.5em;
+  height: 1.5em;
+  vertical-align: middle;
+  content: "";
+  background: no-repeat center center;
+  background-size: 100% 100%;
+}
+
+// Generate series of `.navbar-expand-*` responsive classes for configuring
+// where your navbar collapses.
+.navbar-expand {
+  @each $breakpoint in map-keys($grid-breakpoints) {
+    $next: breakpoint-next($breakpoint, $grid-breakpoints);
+    $infix: breakpoint-infix($next, $grid-breakpoints);
+
+    &#{$infix} {
+      @include media-breakpoint-down($breakpoint) {
+        > .container,
+        > .container-fluid {
+          padding-right: 0;
+          padding-left: 0;
+        }
+      }
+
+      @include media-breakpoint-up($next) {
+        flex-flow: row nowrap;
+        justify-content: flex-start;
+
+        .navbar-nav {
+          flex-direction: row;
+
+          .dropdown-menu {
+            position: absolute;
+          }
+
+          .nav-link {
+            padding-right: $navbar-nav-link-padding-x;
+            padding-left: $navbar-nav-link-padding-x;
+          }
+        }
+
+        // For nesting containers, have to redeclare for alignment purposes
+        > .container,
+        > .container-fluid {
+          flex-wrap: nowrap;
+        }
+
+        .navbar-collapse {
+          display: flex !important;  // stylelint-disable-line declaration-no-important
+
+          // Changes flex-bases to auto because of an IE10 bug
+          flex-basis: auto;
+        }
+
+        .navbar-toggler {
+          display: none;
+        }
+      }
+    }
+  }
+}
+
+
+// Navbar themes
+//
+// Styles for switching between navbars with light or dark background.
+
+// Dark links against a light background
+.navbar-light {
+  .navbar-brand {
+    color: $navbar-light-active-color;
+
+    @include hover-focus {
+      color: $navbar-light-active-color;
+    }
+  }
+
+  .navbar-nav {
+    .nav-link {
+      color: $navbar-light-color;
+
+      @include hover-focus {
+        color: $navbar-light-hover-color;
+      }
+
+      &.disabled {
+        color: $navbar-light-disabled-color;
+      }
+    }
+
+    .show > .nav-link,
+    .active > .nav-link,
+    .nav-link.show,
+    .nav-link.active {
+      color: $navbar-light-active-color;
+    }
+  }
+
+  .navbar-toggler {
+    color: $navbar-light-color;
+    border-color: $navbar-light-toggler-border-color;
+  }
+
+  .navbar-toggler-icon {
+    background-image: $navbar-light-toggler-icon-bg;
+  }
+
+  .navbar-text {
+    color: $navbar-light-color;
+    a {
+      color: $navbar-light-active-color;
+
+      @include hover-focus {
+        color: $navbar-light-active-color;
+      }
+    }
+  }
+}
+
+// White links against a dark background
+.navbar-dark {
+  .navbar-brand {
+    color: $navbar-dark-active-color;
+
+    @include hover-focus {
+      color: $navbar-dark-active-color;
+    }
+  }
+
+  .navbar-nav {
+    .nav-link {
+      color: $navbar-dark-color;
+
+      @include hover-focus {
+        color: $navbar-dark-hover-color;
+      }
+
+      &.disabled {
+        color: $navbar-dark-disabled-color;
+      }
+    }
+
+    .show > .nav-link,
+    .active > .nav-link,
+    .nav-link.show,
+    .nav-link.active {
+      color: $navbar-dark-active-color;
+    }
+  }
+
+  .navbar-toggler {
+    color: $navbar-dark-color;
+    border-color: $navbar-dark-toggler-border-color;
+  }
+
+  .navbar-toggler-icon {
+    background-image: $navbar-dark-toggler-icon-bg;
+  }
+
+  .navbar-text {
+    color: $navbar-dark-color;
+    a {
+      color: $navbar-dark-active-color;
+
+      @include hover-focus {
+        color: $navbar-dark-active-color;
+      }
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/_pagination.scss b/src/sass/bootstrap4/_pagination.scss
new file mode 100644
index 0000000..9349f3f
--- /dev/null
+++ b/src/sass/bootstrap4/_pagination.scss
@@ -0,0 +1,78 @@
+.pagination {
+  display: flex;
+  @include list-unstyled();
+  @include border-radius();
+}
+
+.page-link {
+  position: relative;
+  display: block;
+  padding: $pagination-padding-y $pagination-padding-x;
+  margin-left: -$pagination-border-width;
+  line-height: $pagination-line-height;
+  color: $pagination-color;
+  background-color: $pagination-bg;
+  border: $pagination-border-width solid $pagination-border-color;
+
+  &:hover {
+    z-index: 2;
+    color: $pagination-hover-color;
+    text-decoration: none;
+    background-color: $pagination-hover-bg;
+    border-color: $pagination-hover-border-color;
+  }
+
+  &:focus {
+    z-index: 2;
+    outline: $pagination-focus-outline;
+    box-shadow: $pagination-focus-box-shadow;
+  }
+
+  // Opinionated: add "hand" cursor to non-disabled .page-link elements
+  &:not(:disabled):not(.disabled) {
+    cursor: pointer;
+  }
+}
+
+.page-item {
+  &:first-child {
+    .page-link {
+      margin-left: 0;
+      @include border-left-radius($border-radius);
+    }
+  }
+  &:last-child {
+    .page-link {
+      @include border-right-radius($border-radius);
+    }
+  }
+
+  &.active .page-link {
+    z-index: 1;
+    color: $pagination-active-color;
+    background-color: $pagination-active-bg;
+    border-color: $pagination-active-border-color;
+  }
+
+  &.disabled .page-link {
+    color: $pagination-disabled-color;
+    pointer-events: none;
+    // Opinionated: remove the "hand" cursor set previously for .page-link
+    cursor: auto;
+    background-color: $pagination-disabled-bg;
+    border-color: $pagination-disabled-border-color;
+  }
+}
+
+
+//
+// Sizing
+//
+
+.pagination-lg {
+  @include pagination-size($pagination-padding-y-lg, $pagination-padding-x-lg, $font-size-lg, $line-height-lg, $border-radius-lg);
+}
+
+.pagination-sm {
+  @include pagination-size($pagination-padding-y-sm, $pagination-padding-x-sm, $font-size-sm, $line-height-sm, $border-radius-sm);
+}
diff --git a/src/sass/bootstrap4/_popover.scss b/src/sass/bootstrap4/_popover.scss
new file mode 100644
index 0000000..3ef5f62
--- /dev/null
+++ b/src/sass/bootstrap4/_popover.scss
@@ -0,0 +1,183 @@
+.popover {
+  position: absolute;
+  top: 0;
+  left: 0;
+  z-index: $zindex-popover;
+  display: block;
+  max-width: $popover-max-width;
+  // Our parent element can be arbitrary since tooltips are by default inserted as a sibling of their target element.
+  // So reset our font and text properties to avoid inheriting weird values.
+  @include reset-text();
+  font-size: $popover-font-size;
+  // Allow breaking very long words so they don't overflow the popover's bounds
+  word-wrap: break-word;
+  background-color: $popover-bg;
+  background-clip: padding-box;
+  border: $popover-border-width solid $popover-border-color;
+  @include border-radius($popover-border-radius);
+  @include box-shadow($popover-box-shadow);
+
+  .arrow {
+    position: absolute;
+    display: block;
+    width: $popover-arrow-width;
+    height: $popover-arrow-height;
+    margin: 0 $border-radius-lg;
+
+    &::before,
+    &::after {
+      position: absolute;
+      display: block;
+      content: "";
+      border-color: transparent;
+      border-style: solid;
+    }
+  }
+}
+
+.bs-popover-top {
+  margin-bottom: $popover-arrow-height;
+
+  .arrow {
+    bottom: calc((#{$popover-arrow-height} + #{$popover-border-width}) * -1);
+  }
+
+  .arrow::before,
+  .arrow::after {
+    border-width: $popover-arrow-height ($popover-arrow-width / 2) 0;
+  }
+
+  .arrow::before {
+    bottom: 0;
+    border-top-color: $popover-arrow-outer-color;
+  }
+
+  .arrow::after {
+    bottom: $popover-border-width;
+    border-top-color: $popover-arrow-color;
+  }
+}
+
+.bs-popover-right {
+  margin-left: $popover-arrow-height;
+
+  .arrow {
+    left: calc((#{$popover-arrow-height} + #{$popover-border-width}) * -1);
+    width: $popover-arrow-height;
+    height: $popover-arrow-width;
+    margin: $border-radius-lg 0; // make sure the arrow does not touch the popover's rounded corners
+  }
+
+  .arrow::before,
+  .arrow::after {
+    border-width: ($popover-arrow-width / 2) $popover-arrow-height ($popover-arrow-width / 2) 0;
+  }
+
+  .arrow::before {
+    left: 0;
+    border-right-color: $popover-arrow-outer-color;
+  }
+
+  .arrow::after {
+    left: $popover-border-width;
+    border-right-color: $popover-arrow-color;
+  }
+}
+
+.bs-popover-bottom {
+  margin-top: $popover-arrow-height;
+
+  .arrow {
+    top: calc((#{$popover-arrow-height} + #{$popover-border-width}) * -1);
+  }
+
+  .arrow::before,
+  .arrow::after {
+    border-width: 0 ($popover-arrow-width / 2) $popover-arrow-height ($popover-arrow-width / 2);
+  }
+
+  .arrow::before {
+    top: 0;
+    border-bottom-color: $popover-arrow-outer-color;
+  }
+
+  .arrow::after {
+    top: $popover-border-width;
+    border-bottom-color: $popover-arrow-color;
+  }
+
+  // This will remove the popover-header's border just below the arrow
+  .popover-header::before {
+    position: absolute;
+    top: 0;
+    left: 50%;
+    display: block;
+    width: $popover-arrow-width;
+    margin-left: ($popover-arrow-width / -2);
+    content: "";
+    border-bottom: $popover-border-width solid $popover-header-bg;
+  }
+}
+
+.bs-popover-left {
+  margin-right: $popover-arrow-height;
+
+  .arrow {
+    right: calc((#{$popover-arrow-height} + #{$popover-border-width}) * -1);
+    width: $popover-arrow-height;
+    height: $popover-arrow-width;
+    margin: $border-radius-lg 0; // make sure the arrow does not touch the popover's rounded corners
+  }
+
+  .arrow::before,
+  .arrow::after {
+    border-width: ($popover-arrow-width / 2) 0 ($popover-arrow-width / 2) $popover-arrow-height;
+  }
+
+  .arrow::before {
+    right: 0;
+    border-left-color: $popover-arrow-outer-color;
+  }
+
+  .arrow::after {
+    right: $popover-border-width;
+    border-left-color: $popover-arrow-color;
+  }
+}
+
+.bs-popover-auto {
+  &[x-placement^="top"] {
+    @extend .bs-popover-top;
+  }
+  &[x-placement^="right"] {
+    @extend .bs-popover-right;
+  }
+  &[x-placement^="bottom"] {
+    @extend .bs-popover-bottom;
+  }
+  &[x-placement^="left"] {
+    @extend .bs-popover-left;
+  }
+}
+
+
+// Offset the popover to account for the popover arrow
+.popover-header {
+  padding: $popover-header-padding-y $popover-header-padding-x;
+  margin-bottom: 0; // Reset the default from Reboot
+  font-size: $font-size-base;
+  color: $popover-header-color;
+  background-color: $popover-header-bg;
+  border-bottom: $popover-border-width solid darken($popover-header-bg, 5%);
+  $offset-border-width: calc(#{$border-radius-lg} - #{$popover-border-width});
+  @include border-top-radius($offset-border-width);
+
+  &:empty {
+    display: none;
+  }
+}
+
+.popover-body {
+  padding: $popover-body-padding-y $popover-body-padding-x;
+  color: $popover-body-color;
+}
diff --git a/src/sass/bootstrap4/_print.scss b/src/sass/bootstrap4/_print.scss
new file mode 100644
index 0000000..1df9487
--- /dev/null
+++ b/src/sass/bootstrap4/_print.scss
@@ -0,0 +1,141 @@
+// stylelint-disable declaration-no-important, selector-no-qualifying-type
+
+// Source: https://github.com/h5bp/html5-boilerplate/blob/master/src/css/main.css
+
+// ==========================================================================
+// Print styles.
+// Inlined to avoid the additional HTTP request:
+// https://www.phpied.com/delay-loading-your-print-css/
+// ==========================================================================
+
+@if $enable-print-styles {
+  @media print {
+    *,
+    *::before,
+    *::after {
+      // Bootstrap specific; comment out `color` and `background`
+      //color: $black !important; // Black prints faster
+      text-shadow: none !important;
+      //background: transparent !important;
+      box-shadow: none !important;
+    }
+
+    a {
+      &:not(.btn) {
+        text-decoration: underline;
+      }
+    }
+
+    // Bootstrap specific; comment the following selector out
+    //a[href]::after {
+    //  content: " (" attr(href) ")";
+    //}
+
+    abbr[title]::after {
+      content: " (" attr(title) ")";
+    }
+
+    // Bootstrap specific; comment the following selector out
+    //
+    // Don't show links that are fragment identifiers,
+    // or use the `javascript:` pseudo protocol
+    //
+
+    //a[href^="#"]::after,
+    //a[href^="javascript:"]::after {
+    // content: "";
+    //}
+
+    pre {
+      white-space: pre-wrap !important;
+    }
+    pre,
+    blockquote {
+      border: $border-width solid $gray-500;   // Bootstrap custom code; using `$border-width` instead of 1px
+      page-break-inside: avoid;
+    }
+
+    //
+    // Printing Tables:
+    // http://css-discuss.incutio.com/wiki/Printing_Tables
+    //
+
+    thead {
+      display: table-header-group;
+    }
+
+    tr,
+    img {
+      page-break-inside: avoid;
+    }
+
+    p,
+    h2,
+    h3 {
+      orphans: 3;
+      widows: 3;
+    }
+
+    h2,
+    h3 {
+      page-break-after: avoid;
+    }
+
+    // Bootstrap specific changes start
+
+    // Specify a size and min-width to make printing closer across browsers.
+    // We don't set margin here because it breaks `size` in Chrome. We also
+    // don't use `!important` on `size` as it breaks in Chrome.
+    @page {
+      size: $print-page-size;
+    }
+    body {
+      min-width: $print-body-min-width !important;
+    }
+    .container {
+      min-width: $print-body-min-width !important;
+    }
+
+    // Bootstrap components
+    .navbar {
+      display: none;
+    }
+    .badge {
+      border: $border-width solid $black;
+    }
+
+    .table {
+      border-collapse: collapse !important;
+
+      td,
+      th {
+        background-color: $white !important;
+      }
+    }
+
+    .table-bordered {
+      th,
+      td {
+        border: 1px solid $gray-300 !important;
+      }
+    }
+
+    .table-dark {
+      color: inherit;
+
+      th,
+      td,
+      thead th,
+      tbody + tbody {
+        border-color: $table-border-color;
+      }
+    }
+
+    .table .thead-dark th {
+      color: inherit;
+      border-color: $table-border-color;
+    }
+
+    // Bootstrap specific changes end
+  }
+}
diff --git a/src/sass/bootstrap4/_progress.scss b/src/sass/bootstrap4/_progress.scss
new file mode 100644
index 0000000..0ac3e0c
--- /dev/null
+++ b/src/sass/bootstrap4/_progress.scss
@@ -0,0 +1,34 @@
+@keyframes progress-bar-stripes {
+  from { background-position: $progress-height 0; }
+  to { background-position: 0 0; }
+}
+
+.progress {
+  display: flex;
+  height: $progress-height;
+  overflow: hidden; // force rounded corners by cropping it
+  font-size: $progress-font-size;
+  background-color: $progress-bg;
+  @include border-radius($progress-border-radius);
+  @include box-shadow($progress-box-shadow);
+}
+
+.progress-bar {
+  display: flex;
+  flex-direction: column;
+  justify-content: center;
+  color: $progress-bar-color;
+  text-align: center;
+  white-space: nowrap;
+  background-color: $progress-bar-bg;
+  @include transition($progress-bar-transition);
+}
+
+.progress-bar-striped {
+  @include gradient-striped();
+  background-size: $progress-height $progress-height;
+}
+
+.progress-bar-animated {
+  animation: progress-bar-stripes $progress-bar-animation-timing;
+}
diff --git a/src/sass/bootstrap4/_reboot.scss b/src/sass/bootstrap4/_reboot.scss
new file mode 100644
index 0000000..f297d09
--- /dev/null
+++ b/src/sass/bootstrap4/_reboot.scss
@@ -0,0 +1,483 @@
+// stylelint-disable at-rule-no-vendor-prefix, declaration-no-important, selector-no-qualifying-type, property-no-vendor-prefix
+
+// Reboot
+//
+// Normalization of HTML elements, manually forked from Normalize.css to remove
+// styles targeting irrelevant browsers while applying new styles.
+//
+// Normalize is licensed MIT. https://github.com/necolas/normalize.css
+
+
+// Document
+//
+// 1. Change from `box-sizing: content-box` so that `width` is not affected by `padding` or `border`.
+// 2. Change the default font family in all browsers.
+// 3. Correct the line height in all browsers.
+// 4. Prevent adjustments of font size after orientation changes in IE on Windows Phone and in iOS.
+// 5. Setting @viewport causes scrollbars to overlap content in IE11 and Edge, so
+//    we force a non-overlapping, non-auto-hiding scrollbar to counteract.
+// 6. Change the default tap highlight to be completely transparent in iOS.
+
+*,
+*::before,
+*::after {
+  box-sizing: border-box; // 1
+}
+
+html {
+  font-family: sans-serif; // 2
+  line-height: 1.15; // 3
+  -webkit-text-size-adjust: 100%; // 4
+  -ms-text-size-adjust: 100%; // 4
+  -ms-overflow-style: scrollbar; // 5
+  -webkit-tap-highlight-color: rgba($black, 0); // 6
+}
+
+// IE10+ doesn't honor `<meta name="viewport">` in some cases.
+@at-root {
+  @-ms-viewport {
+    width: device-width;
+  }
+}
+
+// stylelint-disable selector-list-comma-newline-after
+// Shim for "new" HTML5 structural elements to display correctly (IE10, older browsers)
+article, aside, figcaption, figure, footer, header, hgroup, main, nav, section {
+  display: block;
+}
+// stylelint-enable selector-list-comma-newline-after
+
+// Body
+//
+// 1. Remove the margin in all browsers.
+// 2. As a best practice, apply a default `background-color`.
+// 3. Set an explicit initial text-align value so that we can later use the
+//    the `inherit` value on things like `<th>` elements.
+
+body {
+  margin: 0; // 1
+  font-family: $font-family-base;
+  font-size: $font-size-base;
+  font-weight: $font-weight-base;
+  line-height: $line-height-base;
+  color: $body-color;
+  text-align: left; // 3
+  background-color: $body-bg; // 2
+}
+
+// Suppress the focus outline on elements that cannot be accessed via keyboard.
+// This prevents an unwanted focus outline from appearing around elements that
+// might still respond to pointer events.
+//
+// Credit: https://github.com/suitcss/base
+[tabindex="-1"]:focus {
+  outline: 0 !important;
+}
+
+
+// Content grouping
+//
+// 1. Add the correct box sizing in Firefox.
+// 2. Show the overflow in Edge and IE.
+
+hr {
+  box-sizing: content-box; // 1
+  height: 0; // 1
+  overflow: visible; // 2
+}
+
+
+//
+// Typography
+//
+
+// Remove top margins from headings
+//
+// By default, `<h1>`-`<h6>` all receive top and bottom margins. We nuke the top
+// margin for easier control within type scales as it avoids margin collapsing.
+// stylelint-disable selector-list-comma-newline-after
+h1, h2, h3, h4, h5, h6 {
+  margin-top: 0;
+  margin-bottom: $headings-margin-bottom;
+}
+// stylelint-enable selector-list-comma-newline-after
+
+// Reset margins on paragraphs
+//
+// Similarly, the top margin on `<p>`s get reset. However, we also reset the
+// bottom margin to use `rem` units instead of `em`.
+p {
+  margin-top: 0;
+  margin-bottom: $paragraph-margin-bottom;
+}
+
+// Abbreviations
+//
+// 1. Remove the bottom border in Firefox 39-.
+// 2. Add the correct text decoration in Chrome, Edge, IE, Opera, and Safari.
+// 3. Add explicit cursor to indicate changed behavior.
+// 4. Duplicate behavior to the data-* attribute for our tooltip plugin
+
+abbr[title],
+abbr[data-original-title] { // 4
+  text-decoration: underline; // 2
+  text-decoration: underline dotted; // 2
+  cursor: help; // 3
+  border-bottom: 0; // 1
+}
+
+address {
+  margin-bottom: 1rem;
+  font-style: normal;
+  line-height: inherit;
+}
+
+ol,
+ul,
+dl {
+  margin-top: 0;
+  margin-bottom: 1rem;
+}
+
+ol ol,
+ul ul,
+ol ul,
+ul ol {
+  margin-bottom: 0;
+}
+
+dt {
+  font-weight: $dt-font-weight;
+}
+
+dd {
+  margin-bottom: .5rem;
+  margin-left: 0; // Undo browser default
+}
+
+blockquote {
+  margin: 0 0 1rem;
+}
+
+dfn {
+  font-style: italic; // Add the correct font style in Android 4.3-
+}
+
+// stylelint-disable font-weight-notation
+b,
+strong {
+  font-weight: bolder; // Add the correct font weight in Chrome, Edge, and Safari
+}
+// stylelint-enable font-weight-notation
+
+small {
+  font-size: 80%; // Add the correct font size in all browsers
+}
+
+//
+// Prevent `sub` and `sup` elements from affecting the line height in
+// all browsers.
+//
+
+sub,
+sup {
+  position: relative;
+  font-size: 75%;
+  line-height: 0;
+  vertical-align: baseline;
+}
+
+sub { bottom: -.25em; }
+sup { top: -.5em; }
+
+
+//
+// Links
+//
+
+a {
+  color: $link-color;
+  text-decoration: $link-decoration;
+  background-color: transparent; // Remove the gray background on active links in IE 10.
+  -webkit-text-decoration-skip: objects; // Remove gaps in links underline in iOS 8+ and Safari 8+.
+
+  @include hover {
+    color: $link-hover-color;
+    text-decoration: $link-hover-decoration;
+  }
+}
+
+// And undo these styles for placeholder links/named anchors (without href)
+// which have not been made explicitly keyboard-focusable (without tabindex).
+// It would be more straightforward to just use a[href] in previous block, but that
+// causes specificity issues in many other styles that are too complex to fix.
+// See https://github.com/twbs/bootstrap/issues/19402
+
+a:not([href]):not([tabindex]) {
+  color: inherit;
+  text-decoration: none;
+
+  @include hover-focus {
+    color: inherit;
+    text-decoration: none;
+  }
+
+  &:focus {
+    outline: 0;
+  }
+}
+
+
+//
+// Code
+//
+
+pre,
+code,
+kbd,
+samp {
+  font-family: $font-family-monospace;
+  font-size: 1em; // Correct the odd `em` font sizing in all browsers.
+}
+
+pre {
+  // Remove browser default top margin
+  margin-top: 0;
+  // Reset browser default of `1em` to use `rem`s
+  margin-bottom: 1rem;
+  // Don't allow content to break outside
+  overflow: auto;
+  // We have @viewport set which causes scrollbars to overlap content in IE11 and Edge, so
+  // we force a non-overlapping, non-auto-hiding scrollbar to counteract.
+  -ms-overflow-style: scrollbar;
+}
+
+
+//
+// Figures
+//
+
+figure {
+  // Apply a consistent margin strategy (matches our type styles).
+  margin: 0 0 1rem;
+}
+
+
+//
+// Images and content
+//
+
+img {
+  vertical-align: middle;
+  border-style: none; // Remove the border on images inside links in IE 10-.
+}
+
+svg {
+  // Workaround for the SVG overflow bug in IE10/11 is still required.
+  // See https://github.com/twbs/bootstrap/issues/26878
+  overflow: hidden;
+  vertical-align: middle;
+}
+
+
+//
+// Tables
+//
+
+table {
+  border-collapse: collapse; // Prevent double borders
+}
+
+caption {
+  padding-top: $table-cell-padding;
+  padding-bottom: $table-cell-padding;
+  color: $table-caption-color;
+  text-align: left;
+  caption-side: bottom;
+}
+
+th {
+  // Matches default `<td>` alignment by inheriting from the `<body>`, or the
+  // closest parent with a set `text-align`.
+  text-align: inherit;
+}
+
+
+//
+// Forms
+//
+
+label {
+  // Allow labels to use `margin` for spacing.
+  display: inline-block;
+  margin-bottom: $label-margin-bottom;
+}
+
+// Remove the default `border-radius` that macOS Chrome adds.
+//
+// Details at https://github.com/twbs/bootstrap/issues/24093
+button {
+  border-radius: 0;
+}
+
+// Work around a Firefox/IE bug where the transparent `button` background
+// results in a loss of the default `button` focus styles.
+//
+// Credit: https://github.com/suitcss/base/
+button:focus {
+  outline: 1px dotted;
+  outline: 5px auto -webkit-focus-ring-color;
+}
+
+input,
+button,
+select,
+optgroup,
+textarea {
+  margin: 0; // Remove the margin in Firefox and Safari
+  font-family: inherit;
+  font-size: inherit;
+  line-height: inherit;
+}
+
+button,
+input {
+  overflow: visible; // Show the overflow in Edge
+}
+
+button,
+select {
+  text-transform: none; // Remove the inheritance of text transform in Firefox
+}
+
+// 1. Prevent a WebKit bug where (2) destroys native `audio` and `video`
+//    controls in Android 4.
+// 2. Correct the inability to style clickable types in iOS and Safari.
+button,
+html [type="button"], // 1
+[type="reset"],
+[type="submit"] {
+  -webkit-appearance: button; // 2
+}
+
+// Remove inner border and padding from Firefox, but don't restore the outline like Normalize.
+button::-moz-focus-inner,
+[type="button"]::-moz-focus-inner,
+[type="reset"]::-moz-focus-inner,
+[type="submit"]::-moz-focus-inner {
+  padding: 0;
+  border-style: none;
+}
+
+input[type="radio"],
+input[type="checkbox"] {
+  box-sizing: border-box; // 1. Add the correct box sizing in IE 10-
+  padding: 0; // 2. Remove the padding in IE 10-
+}
+
+
+input[type="date"],
+input[type="time"],
+input[type="datetime-local"],
+input[type="month"] {
+  // Remove the default appearance of temporal inputs to avoid a Mobile Safari
+  // bug where setting a custom line-height prevents text from being vertically
+  // centered within the input.
+  // See https://bugs.webkit.org/show_bug.cgi?id=139848
+  // and https://github.com/twbs/bootstrap/issues/11266
+  -webkit-appearance: listbox;
+}
+
+textarea {
+  overflow: auto; // Remove the default vertical scrollbar in IE.
+  // Textareas should really only resize vertically so they don't break their (horizontal) containers.
+  resize: vertical;
+}
+
+fieldset {
+  // Browsers set a default `min-width: min-content;` on fieldsets,
+  // unlike e.g. `<div>`s, which have `min-width: 0;` by default.
+  // So we reset that to ensure fieldsets behave more like a standard block element.
+  // See https://github.com/twbs/bootstrap/issues/12359
+  // and https://html.spec.whatwg.org/multipage/#the-fieldset-and-legend-elements
+  min-width: 0;
+  // Reset the default outline behavior of fieldsets so they don't affect page layout.
+  padding: 0;
+  margin: 0;
+  border: 0;
+}
+
+// 1. Correct the text wrapping in Edge and IE.
+// 2. Correct the color inheritance from `fieldset` elements in IE.
+legend {
+  display: block;
+  width: 100%;
+  max-width: 100%; // 1
+  padding: 0;
+  margin-bottom: .5rem;
+  font-size: 1.5rem;
+  line-height: inherit;
+  color: inherit; // 2
+  white-space: normal; // 1
+}
+
+progress {
+  vertical-align: baseline; // Add the correct vertical alignment in Chrome, Firefox, and Opera.
+}
+
+// Correct the cursor style of increment and decrement buttons in Chrome.
+[type="number"]::-webkit-inner-spin-button,
+[type="number"]::-webkit-outer-spin-button {
+  height: auto;
+}
+
+[type="search"] {
+  // This overrides the extra rounded corners on search inputs in iOS so that our
+  // `.form-control` class can properly style them. Note that this cannot simply
+  // be added to `.form-control` as it's not specific enough. For details, see
+  // https://github.com/twbs/bootstrap/issues/11586.
+  outline-offset: -2px; // 2. Correct the outline style in Safari.
+  -webkit-appearance: none;
+}
+
+//
+// Remove the inner padding and cancel buttons in Chrome and Safari on macOS.
+//
+
+[type="search"]::-webkit-search-cancel-button,
+[type="search"]::-webkit-search-decoration {
+  -webkit-appearance: none;
+}
+
+//
+// 1. Correct the inability to style clickable types in iOS and Safari.
+// 2. Change font properties to `inherit` in Safari.
+//
+
+::-webkit-file-upload-button {
+  font: inherit; // 2
+  -webkit-appearance: button; // 1
+}
+
+//
+// Correct element displays
+//
+
+output {
+  display: inline-block;
+}
+
+summary {
+  display: list-item; // Add the correct display in all browsers
+  cursor: pointer;
+}
+
+template {
+  display: none; // Add the correct display in IE
+}
+
+// Always hide an element with the `hidden` HTML attribute (from PureCSS).
+// Needed for proper display in IE 10-.
+[hidden] {
+  display: none !important;
+}
diff --git a/src/sass/bootstrap4/_root.scss b/src/sass/bootstrap4/_root.scss
new file mode 100644
index 0000000..ad550df
--- /dev/null
+++ b/src/sass/bootstrap4/_root.scss
@@ -0,0 +1,19 @@
+:root {
+  // Custom variable values only support SassScript inside `#{}`.
+  @each $color, $value in $colors {
+    --#{$color}: #{$value};
+  }
+
+  @each $color, $value in $theme-colors {
+    --#{$color}: #{$value};
+  }
+
+  @each $bp, $value in $grid-breakpoints {
+    --breakpoint-#{$bp}: #{$value};
+  }
+
+  // Use `inspect` for lists so that quoted items keep the quotes.
+  // See https://github.com/sass/sass/issues/2383#issuecomment-336349172
+  --font-family-sans-serif: #{inspect($font-family-sans-serif)};
+  --font-family-monospace: #{inspect($font-family-monospace)};
+}
diff --git a/src/sass/bootstrap4/_tables.scss b/src/sass/bootstrap4/_tables.scss
new file mode 100644
index 0000000..5fa6a86
--- /dev/null
+++ b/src/sass/bootstrap4/_tables.scss
@@ -0,0 +1,187 @@
+//
+// Basic Bootstrap table
+//
+
+.table {
+  width: 100%;
+  margin-bottom: $spacer;
+  background-color: $table-bg; // Reset for nesting within parents with `background-color`.
+
+  th,
+  td {
+    padding: $table-cell-padding;
+    vertical-align: top;
+    border-top: $table-border-width solid $table-border-color;
+  }
+
+  thead th {
+    vertical-align: bottom;
+    border-bottom: (2 * $table-border-width) solid $table-border-color;
+  }
+
+  tbody + tbody {
+    border-top: (2 * $table-border-width) solid $table-border-color;
+  }
+
+  .table {
+    background-color: $body-bg;
+  }
+}
+
+
+//
+// Condensed table w/ half padding
+//
+
+.table-sm {
+  th,
+  td {
+    padding: $table-cell-padding-sm;
+  }
+}
+
+
+// Border versions
+//
+// Add or remove borders all around the table and between all the columns.
+
+.table-bordered {
+  border: $table-border-width solid $table-border-color;
+
+  th,
+  td {
+    border: $table-border-width solid $table-border-color;
+  }
+
+  thead {
+    th,
+    td {
+      border-bottom-width: (2 * $table-border-width);
+    }
+  }
+}
+
+.table-borderless {
+  th,
+  td,
+  thead th,
+  tbody + tbody {
+    border: 0;
+  }
+}
+
+// Zebra-striping
+//
+// Default zebra-stripe styles (alternating gray and transparent backgrounds)
+
+.table-striped {
+  tbody tr:nth-of-type(#{$table-striped-order}) {
+    background-color: $table-accent-bg;
+  }
+}
+
+
+// Hover effect
+//
+// Placed here since it has to come after the potential zebra striping
+
+.table-hover {
+  tbody tr {
+    @include hover {
+      background-color: $table-hover-bg;
+    }
+  }
+}
+
+
+// Table backgrounds
+//
+// Exact selectors below required to override `.table-striped` and prevent
+// inheritance to nested tables.
+
+@each $color, $value in $theme-colors {
+  @include table-row-variant($color, theme-color-level($color, -9));
+}
+
+@include table-row-variant(active, $table-active-bg);
+
+
+// Dark styles
+//
+// Same table markup, but inverted color scheme: dark background and light text.
+
+// stylelint-disable-next-line no-duplicate-selectors
+.table {
+  .thead-dark {
+    th {
+      color: $table-dark-color;
+      background-color: $table-dark-bg;
+      border-color: $table-dark-border-color;
+    }
+  }
+
+  .thead-light {
+    th {
+      color: $table-head-color;
+      background-color: $table-head-bg;
+      border-color: $table-border-color;
+    }
+  }
+}
+
+.table-dark {
+  color: $table-dark-color;
+  background-color: $table-dark-bg;
+
+  th,
+  td,
+  thead th {
+    border-color: $table-dark-border-color;
+  }
+
+  &.table-bordered {
+    border: 0;
+  }
+
+  &.table-striped {
+    tbody tr:nth-of-type(odd) {
+      background-color: $table-dark-accent-bg;
+    }
+  }
+
+  &.table-hover {
+    tbody tr {
+      @include hover {
+        background-color: $table-dark-hover-bg;
+      }
+    }
+  }
+}
+
+
+// Responsive tables
+//
+// Generate series of `.table-responsive-*` classes for configuring the screen
+// size of where your table will overflow.
+
+.table-responsive {
+  @each $breakpoint in map-keys($grid-breakpoints) {
+    $next: breakpoint-next($breakpoint, $grid-breakpoints);
+    $infix: breakpoint-infix($next, $grid-breakpoints);
+
+    &#{$infix} {
+      @include media-breakpoint-down($breakpoint) {
+        display: block;
+        width: 100%;
+        overflow-x: auto;
+        -webkit-overflow-scrolling: touch;
+        -ms-overflow-style: -ms-autohiding-scrollbar; // See https://github.com/twbs/bootstrap/pull/10057
+
+        // Prevent double border on horizontal scroll due to use of `display: block;`
+        > .table-bordered {
+          border: 0;
+        }
+      }
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/_tooltip.scss b/src/sass/bootstrap4/_tooltip.scss
new file mode 100644
index 0000000..1286ebf
--- /dev/null
+++ b/src/sass/bootstrap4/_tooltip.scss
@@ -0,0 +1,115 @@
+// Base class
+.tooltip {
+  position: absolute;
+  z-index: $zindex-tooltip;
+  display: block;
+  margin: $tooltip-margin;
+  // Our parent element can be arbitrary since tooltips are by default inserted as a sibling of their target element.
+  // So reset our font and text properties to avoid inheriting weird values.
+  @include reset-text();
+  font-size: $tooltip-font-size;
+  // Allow breaking very long words so they don't overflow the tooltip's bounds
+  word-wrap: break-word;
+  opacity: 0;
+
+  &.show { opacity: $tooltip-opacity; }
+
+  .arrow {
+    position: absolute;
+    display: block;
+    width: $tooltip-arrow-width;
+    height: $tooltip-arrow-height;
+
+    &::before {
+      position: absolute;
+      content: "";
+      border-color: transparent;
+      border-style: solid;
+    }
+  }
+}
+
+.bs-tooltip-top {
+  padding: $tooltip-arrow-height 0;
+
+  .arrow {
+    bottom: 0;
+
+    &::before {
+      top: 0;
+      border-width: $tooltip-arrow-height ($tooltip-arrow-width / 2) 0;
+      border-top-color: $tooltip-arrow-color;
+    }
+  }
+}
+
+.bs-tooltip-right {
+  padding: 0 $tooltip-arrow-height;
+
+  .arrow {
+    left: 0;
+    width: $tooltip-arrow-height;
+    height: $tooltip-arrow-width;
+
+    &::before {
+      right: 0;
+      border-width: ($tooltip-arrow-width / 2) $tooltip-arrow-height ($tooltip-arrow-width / 2) 0;
+      border-right-color: $tooltip-arrow-color;
+    }
+  }
+}
+
+.bs-tooltip-bottom {
+  padding: $tooltip-arrow-height 0;
+
+  .arrow {
+    top: 0;
+
+    &::before {
+      bottom: 0;
+      border-width: 0 ($tooltip-arrow-width / 2) $tooltip-arrow-height;
+      border-bottom-color: $tooltip-arrow-color;
+    }
+  }
+}
+
+.bs-tooltip-left {
+  padding: 0 $tooltip-arrow-height;
+
+  .arrow {
+    right: 0;
+    width: $tooltip-arrow-height;
+    height: $tooltip-arrow-width;
+
+    &::before {
+      left: 0;
+      border-width: ($tooltip-arrow-width / 2) 0 ($tooltip-arrow-width / 2) $tooltip-arrow-height;
+      border-left-color: $tooltip-arrow-color;
+    }
+  }
+}
+
+.bs-tooltip-auto {
+  &[x-placement^="top"] {
+    @extend .bs-tooltip-top;
+  }
+  &[x-placement^="right"] {
+    @extend .bs-tooltip-right;
+  }
+  &[x-placement^="bottom"] {
+    @extend .bs-tooltip-bottom;
+  }
+  &[x-placement^="left"] {
+    @extend .bs-tooltip-left;
+  }
+}
+
+// Wrapper for the tooltip content
+.tooltip-inner {
+  max-width: $tooltip-max-width;
+  padding: $tooltip-padding-y $tooltip-padding-x;
+  color: $tooltip-color;
+  text-align: center;
+  background-color: $tooltip-bg;
+  @include border-radius($tooltip-border-radius);
+}
diff --git a/src/sass/bootstrap4/_transitions.scss b/src/sass/bootstrap4/_transitions.scss
new file mode 100644
index 0000000..c8d91e2
--- /dev/null
+++ b/src/sass/bootstrap4/_transitions.scss
@@ -0,0 +1,22 @@
+// stylelint-disable selector-no-qualifying-type
+
+.fade {
+  @include transition($transition-fade);
+
+  &:not(.show) {
+    opacity: 0;
+  }
+}
+
+.collapse {
+  &:not(.show) {
+    display: none;
+  }
+}
+
+.collapsing {
+  position: relative;
+  height: 0;
+  overflow: hidden;
+  @include transition($transition-collapse);
+}
diff --git a/src/sass/bootstrap4/_type.scss b/src/sass/bootstrap4/_type.scss
new file mode 100644
index 0000000..57d610f
--- /dev/null
+++ b/src/sass/bootstrap4/_type.scss
@@ -0,0 +1,125 @@
+// stylelint-disable declaration-no-important, selector-list-comma-newline-after
+
+//
+// Headings
+//
+
+h1, h2, h3, h4, h5, h6,
+.h1, .h2, .h3, .h4, .h5, .h6 {
+  margin-bottom: $headings-margin-bottom;
+  font-family: $headings-font-family;
+  font-weight: $headings-font-weight;
+  line-height: $headings-line-height;
+  color: $headings-color;
+}
+
+h1, .h1 { font-size: $h1-font-size; }
+h2, .h2 { font-size: $h2-font-size; }
+h3, .h3 { font-size: $h3-font-size; }
+h4, .h4 { font-size: $h4-font-size; }
+h5, .h5 { font-size: $h5-font-size; }
+h6, .h6 { font-size: $h6-font-size; }
+
+.lead {
+  font-size: $lead-font-size;
+  font-weight: $lead-font-weight;
+}
+
+// Type display classes
+.display-1 {
+  font-size: $display1-size;
+  font-weight: $display1-weight;
+  line-height: $display-line-height;
+}
+.display-2 {
+  font-size: $display2-size;
+  font-weight: $display2-weight;
+  line-height: $display-line-height;
+}
+.display-3 {
+  font-size: $display3-size;
+  font-weight: $display3-weight;
+  line-height: $display-line-height;
+}
+.display-4 {
+  font-size: $display4-size;
+  font-weight: $display4-weight;
+  line-height: $display-line-height;
+}
+
+
+//
+// Horizontal rules
+//
+
+hr {
+  margin-top: $hr-margin-y;
+  margin-bottom: $hr-margin-y;
+  border: 0;
+  border-top: $hr-border-width solid $hr-border-color;
+}
+
+
+//
+// Emphasis
+//
+
+small,
+.small {
+  font-size: $small-font-size;
+  font-weight: $font-weight-normal;
+}
+
+mark,
+.mark {
+  padding: $mark-padding;
+  background-color: $mark-bg;
+}
+
+
+//
+// Lists
+//
+
+.list-unstyled {
+  @include list-unstyled;
+}
+
+// Inline turns list items into inline-block
+.list-inline {
+  @include list-unstyled;
+}
+.list-inline-item {
+  display: inline-block;
+
+  &:not(:last-child) {
+    margin-right: $list-inline-padding;
+  }
+}
+
+
+//
+// Misc
+//
+
+// Builds on `abbr`
+.initialism {
+  font-size: 90%;
+  text-transform: uppercase;
+}
+
+// Blockquotes
+.blockquote {
+  margin-bottom: $spacer;
+  font-size: $blockquote-font-size;
+}
+
+.blockquote-footer {
+  display: block;
+  font-size: 80%; // back to default font-size
+  color: $blockquote-small-color;
+
+  &::before {
+    content: "\2014 \00A0"; // em dash, nbsp
+  }
+}
diff --git a/src/sass/bootstrap4/_utilities.scss b/src/sass/bootstrap4/_utilities.scss
new file mode 100644
index 0000000..6c7a7cd
--- /dev/null
+++ b/src/sass/bootstrap4/_utilities.scss
@@ -0,0 +1,15 @@
+@import "utilities/align";
+@import "utilities/background";
+@import "utilities/borders";
+@import "utilities/clearfix";
+@import "utilities/display";
+@import "utilities/embed";
+@import "utilities/flex";
+@import "utilities/float";
+@import "utilities/position";
+@import "utilities/screenreaders";
+@import "utilities/shadows";
+@import "utilities/sizing";
+@import "utilities/spacing";
+@import "utilities/text";
+@import "utilities/visibility";
diff --git a/src/sass/bootstrap4/_variables.scss b/src/sass/bootstrap4/_variables.scss
new file mode 100644
index 0000000..5cf118f
--- /dev/null
+++ b/src/sass/bootstrap4/_variables.scss
@@ -0,0 +1,952 @@
+// Variables
+//
+// Variables should follow the `$component-state-property-size` formula for
+// consistent naming. Ex: $nav-link-disabled-color and $modal-content-box-shadow-xs.
+
+
+//
+// Color system
+//
+
+$white:    #fff !default;
+$gray-100: #f8f9fa !default;
+$gray-200: #e9ecef !default;
+$gray-300: #dee2e6 !default;
+$gray-400: #ced4da !default;
+$gray-500: #adb5bd !default;
+$gray-600: #6c757d !default;
+$gray-700: #495057 !default;
+$gray-800: #343a40 !default;
+$gray-900: #212529 !default;
+$black:    #000 !default;
+
+$grays: () !default;
+// stylelint-disable-next-line scss/dollar-variable-default
+$grays: map-merge(
+  (
+    "100": $gray-100,
+    "200": $gray-200,
+    "300": $gray-300,
+    "400": $gray-400,
+    "500": $gray-500,
+    "600": $gray-600,
+    "700": $gray-700,
+    "800": $gray-800,
+    "900": $gray-900
+  ),
+  $grays
+);
+
+
+$blue:    #007bff !default;
+$indigo:  #6610f2 !default;
+$purple:  #6f42c1 !default;
+$pink:    #e83e8c !default;
+$red:     #dc3545 !default;
+$orange:  #fd7e14 !default;
+$yellow:  #ffc107 !default;
+$green:   #28a745 !default;
+$teal:    #20c997 !default;
+$cyan:    #17a2b8 !default;
+
+$colors: () !default;
+// stylelint-disable-next-line scss/dollar-variable-default
+$colors: map-merge(
+  (
+    "blue":       $blue,
+    "indigo":     $indigo,
+    "purple":     $purple,
+    "pink":       $pink,
+    "red":        $red,
+    "orange":     $orange,
+    "yellow":     $yellow,
+    "green":      $green,
+    "teal":       $teal,
+    "cyan":       $cyan,
+    "white":      $white,
+    "gray":       $gray-600,
+    "gray-dark":  $gray-800
+  ),
+  $colors
+);
+
+$primary:       $blue !default;
+$secondary:     $gray-600 !default;
+$success:       $green !default;
+$info:          $cyan !default;
+$warning:       $yellow !default;
+$danger:        $red !default;
+$light:         $gray-100 !default;
+$dark:          $gray-800 !default;
+
+$theme-colors: () !default;
+// stylelint-disable-next-line scss/dollar-variable-default
+$theme-colors: map-merge(
+  (
+    "primary":    $primary,
+    "secondary":  $secondary,
+    "success":    $success,
+    "info":       $info,
+    "warning":    $warning,
+    "danger":     $danger,
+    "light":      $light,
+    "dark":       $dark
+  ),
+  $theme-colors
+);
+
+// Set a specific jump point for requesting color jumps
+$theme-color-interval:      8% !default;
+
+// The yiq lightness value that determines when the lightness of color changes from "dark" to "light". Acceptable values are between 0 and 255.
+$yiq-contrasted-threshold:  150 !default;
+
+// Customize the light and dark text colors for use in our YIQ color contrast function.
+$yiq-text-dark:             $gray-900 !default;
+$yiq-text-light:            $white !default;
+
+// Options
+//
+// Quickly modify global styling by enabling or disabling optional features.
+
+$enable-caret:              true !default;
+$enable-rounded:            true !default;
+$enable-shadows:            false !default;
+$enable-gradients:          false !default;
+$enable-transitions:        true !default;
+$enable-hover-media-query:  false !default; // Deprecated, no longer affects any compiled CSS
+$enable-grid-classes:       true !default;
+$enable-print-styles:       true !default;
+
+
+// Spacing
+//
+// Control the default styling of most Bootstrap elements by modifying these
+// variables. Mostly focused on spacing.
+// You can add more entries to the $spacers map, should you need more variation.
+
+$spacer: 1rem !default;
+$spacers: () !default;
+// stylelint-disable-next-line scss/dollar-variable-default
+$spacers: map-merge(
+  (
+    0: 0,
+    1: ($spacer * .25),
+    2: ($spacer * .5),
+    3: $spacer,
+    4: ($spacer * 1.5),
+    5: ($spacer * 3)
+  ),
+  $spacers
+);
+
+// This variable affects the `.h-*` and `.w-*` classes.
+$sizes: () !default;
+// stylelint-disable-next-line scss/dollar-variable-default
+$sizes: map-merge(
+  (
+    25: 25%,
+    50: 50%,
+    75: 75%,
+    100: 100%,
+    auto: auto
+  ),
+  $sizes
+);
+
+// Body
+//
+// Settings for the `<body>` element.
+
+$body-bg:                   $white !default;
+$body-color:                $gray-900 !default;
+
+// Links
+//
+// Style anchor elements.
+
+$link-color:                theme-color("primary") !default;
+$link-decoration:           none !default;
+$link-hover-color:          darken($link-color, 15%) !default;
+$link-hover-decoration:     underline !default;
+
+// Paragraphs
+//
+// Style p element.
+
+$paragraph-margin-bottom:   1rem !default;
+
+
+// Grid breakpoints
+//
+// Define the minimum dimensions at which your layout will change,
+// adapting to different screen sizes, for use in media queries.
+
+$grid-breakpoints: (
+  xs: 0,
+  sm: 576px,
+  md: 768px,
+  lg: 992px,
+  xl: 1200px
+) !default;
+
+@include _assert-ascending($grid-breakpoints, "$grid-breakpoints");
+@include _assert-starts-at-zero($grid-breakpoints);
+
+
+// Grid containers
+//
+// Define the maximum width of `.container` for different screen sizes.
+
+$container-max-widths: (
+  sm: 540px,
+  md: 720px,
+  lg: 960px,
+  xl: 1140px
+) !default;
+
+@include _assert-ascending($container-max-widths, "$container-max-widths");
+
+
+// Grid columns
+//
+// Set the number of columns and specify the width of the gutters.
+
+$grid-columns:                12 !default;
+$grid-gutter-width:           30px !default;
+
+// Components
+//
+// Define common padding and border radius sizes and more.
+
+$line-height-lg:              1.5 !default;
+$line-height-sm:              1.5 !default;
+
+$border-width:                1px !default;
+$border-color:                $gray-300 !default;
+
+$border-radius:               .25rem !default;
+$border-radius-lg:            .3rem !default;
+$border-radius-sm:            .2rem !default;
+
+$box-shadow-sm:               0 .125rem .25rem rgba($black, .075) !default;
+$box-shadow:                  0 .5rem 1rem rgba($black, .15) !default;
+$box-shadow-lg:               0 1rem 3rem rgba($black, .175) !default;
+
+$component-active-color:      $white !default;
+$component-active-bg:         theme-color("primary") !default;
+
+$caret-width:                 .3em !default;
+
+$transition-base:             all .2s ease-in-out !default;
+$transition-fade:             opacity .15s linear !default;
+$transition-collapse:         height .35s ease !default;
+
+
+// Fonts
+//
+// Font, line-height, and color for body text, headings, and more.
+
+// stylelint-disable value-keyword-case
+$font-family-sans-serif:      -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji" !default;
+$font-family-monospace:       SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace !default;
+$font-family-base:            $font-family-sans-serif !default;
+// stylelint-enable value-keyword-case
+
+$font-size-base:              1rem !default; // Assumes the browser default, typically `16px`
+$font-size-lg:                ($font-size-base * 1.25) !default;
+$font-size-sm:                ($font-size-base * .875) !default;
+
+$font-weight-light:           300 !default;
+$font-weight-normal:          400 !default;
+$font-weight-bold:            700 !default;
+
+$font-weight-base:            $font-weight-normal !default;
+$line-height-base:            1.5 !default;
+
+$h1-font-size:                $font-size-base * 2.5 !default;
+$h2-font-size:                $font-size-base * 2 !default;
+$h3-font-size:                $font-size-base * 1.75 !default;
+$h4-font-size:                $font-size-base * 1.5 !default;
+$h5-font-size:                $font-size-base * 1.25 !default;
+$h6-font-size:                $font-size-base !default;
+
+$headings-margin-bottom:      ($spacer / 2) !default;
+$headings-font-family:        inherit !default;
+$headings-font-weight:        500 !default;
+$headings-line-height:        1.2 !default;
+$headings-color:              inherit !default;
+
+$display1-size:               6rem !default;
+$display2-size:               5.5rem !default;
+$display3-size:               4.5rem !default;
+$display4-size:               3.5rem !default;
+
+$display1-weight:             300 !default;
+$display2-weight:             300 !default;
+$display3-weight:             300 !default;
+$display4-weight:             300 !default;
+$display-line-height:         $headings-line-height !default;
+
+$lead-font-size:              ($font-size-base * 1.25) !default;
+$lead-font-weight:            300 !default;
+
+$small-font-size:             80% !default;
+
+$text-muted:                  $gray-600 !default;
+
+$blockquote-small-color:      $gray-600 !default;
+$blockquote-font-size:        ($font-size-base * 1.25) !default;
+
+$hr-border-color:             rgba($black, .1) !default;
+$hr-border-width:             $border-width !default;
+
+$mark-padding:                .2em !default;
+
+$dt-font-weight:              $font-weight-bold !default;
+
+$kbd-box-shadow:              inset 0 -.1rem 0 rgba($black, .25) !default;
+$nested-kbd-font-weight:      $font-weight-bold !default;
+
+$list-inline-padding:         .5rem !default;
+
+$mark-bg:                     #fcf8e3 !default;
+
+$hr-margin-y:                 $spacer !default;
+
+
+// Tables
+//
+// Customizes the `.table` component with basic values, each used across all table variations.
+
+$table-cell-padding:          .75rem !default;
+$table-cell-padding-sm:       .3rem !default;
+
+$table-bg:                    transparent !default;
+$table-accent-bg:             rgba($black, .05) !default;
+$table-hover-bg:              rgba($black, .075) !default;
+$table-active-bg:             $table-hover-bg !default;
+
+$table-border-width:          $border-width !default;
+$table-border-color:          $gray-300 !default;
+
+$table-head-bg:               $gray-200 !default;
+$table-head-color:            $gray-700 !default;
+
+$table-dark-bg:               $gray-900 !default;
+$table-dark-accent-bg:        rgba($white, .05) !default;
+$table-dark-hover-bg:         rgba($white, .075) !default;
+$table-dark-border-color:     lighten($gray-900, 7.5%) !default;
+$table-dark-color:            $body-bg !default;
+
+$table-striped-order:         odd !default;
+
+$table-caption-color:         $text-muted !default;
+
+// Buttons + Forms
+//
+// Shared variables that are reassigned to `$input-` and `$btn-` specific variables.
+
+$input-btn-padding-y:         .375rem !default;
+$input-btn-padding-x:         .75rem !default;
+$input-btn-line-height:       $line-height-base !default;
+
+$input-btn-focus-width:       .2rem !default;
+$input-btn-focus-color:       rgba($component-active-bg, .25) !default;
+$input-btn-focus-box-shadow:  0 0 0 $input-btn-focus-width $input-btn-focus-color !default;
+
+$input-btn-padding-y-sm:      .25rem !default;
+$input-btn-padding-x-sm:      .5rem !default;
+$input-btn-line-height-sm:    $line-height-sm !default;
+
+$input-btn-padding-y-lg:      .5rem !default;
+$input-btn-padding-x-lg:      1rem !default;
+$input-btn-line-height-lg:    $line-height-lg !default;
+
+$input-btn-border-width:      $border-width !default;
+
+
+// Buttons
+//
+// For each of Bootstrap's buttons, define text, background, and border color.
+
+$btn-padding-y:               $input-btn-padding-y !default;
+$btn-padding-x:               $input-btn-padding-x !default;
+$btn-line-height:             $input-btn-line-height !default;
+
+$btn-padding-y-sm:            $input-btn-padding-y-sm !default;
+$btn-padding-x-sm:            $input-btn-padding-x-sm !default;
+$btn-line-height-sm:          $input-btn-line-height-sm !default;
+
+$btn-padding-y-lg:            $input-btn-padding-y-lg !default;
+$btn-padding-x-lg:            $input-btn-padding-x-lg !default;
+$btn-line-height-lg:          $input-btn-line-height-lg !default;
+
+$btn-border-width:            $input-btn-border-width !default;
+
+$btn-font-weight:             $font-weight-normal !default;
+$btn-box-shadow:              inset 0 1px 0 rgba($white, .15), 0 1px 1px rgba($black, .075) !default;
+$btn-focus-width:             $input-btn-focus-width !default;
+$btn-focus-box-shadow:        $input-btn-focus-box-shadow !default;
+$btn-disabled-opacity:        .65 !default;
+$btn-active-box-shadow:       inset 0 3px 5px rgba($black, .125) !default;
+
+$btn-link-disabled-color:     $gray-600 !default;
+
+$btn-block-spacing-y:         .5rem !default;
+
+// Allows for customizing button radius independently from global border radius
+$btn-border-radius:           $border-radius !default;
+$btn-border-radius-lg:        $border-radius-lg !default;
+$btn-border-radius-sm:        $border-radius-sm !default;
+
+$btn-transition:              color .15s ease-in-out, background-color .15s ease-in-out, border-color .15s ease-in-out, box-shadow .15s ease-in-out !default;
+
+
+// Forms
+
+$label-margin-bottom:                   .5rem !default;
+
+$input-padding-y:                       $input-btn-padding-y !default;
+$input-padding-x:                       $input-btn-padding-x !default;
+$input-line-height:                     $input-btn-line-height !default;
+
+$input-padding-y-sm:                    $input-btn-padding-y-sm !default;
+$input-padding-x-sm:                    $input-btn-padding-x-sm !default;
+$input-line-height-sm:                  $input-btn-line-height-sm !default;
+
+$input-padding-y-lg:                    $input-btn-padding-y-lg !default;
+$input-padding-x-lg:                    $input-btn-padding-x-lg !default;
+$input-line-height-lg:                  $input-btn-line-height-lg !default;
+
+$input-bg:                              $white !default;
+$input-disabled-bg:                     $gray-200 !default;
+
+$input-color:                           $gray-700 !default;
+$input-border-color:                    $gray-400 !default;
+$input-border-width:                    $input-btn-border-width !default;
+$input-box-shadow:                      inset 0 1px 1px rgba($black, .075) !default;
+
+$input-border-radius:                   $border-radius !default;
+$input-border-radius-lg:                $border-radius-lg !default;
+$input-border-radius-sm:                $border-radius-sm !default;
+
+$input-focus-bg:                        $input-bg !default;
+$input-focus-border-color:              lighten($component-active-bg, 25%) !default;
+$input-focus-color:                     $input-color !default;
+$input-focus-width:                     $input-btn-focus-width !default;
+$input-focus-box-shadow:                $input-btn-focus-box-shadow !default;
+
+$input-placeholder-color:               $gray-600 !default;
+$input-plaintext-color:                 $body-color !default;
+
+$input-height-border:                   $input-border-width * 2 !default;
+
+$input-height-inner:                    ($font-size-base * $input-btn-line-height) + ($input-btn-padding-y * 2) !default;
+$input-height:                          calc(#{$input-height-inner} + #{$input-height-border}) !default;
+
+$input-height-inner-sm:                 ($font-size-sm * $input-btn-line-height-sm) + ($input-btn-padding-y-sm * 2) !default;
+$input-height-sm:                       calc(#{$input-height-inner-sm} + #{$input-height-border}) !default;
+
+$input-height-inner-lg:                 ($font-size-lg * $input-btn-line-height-lg) + ($input-btn-padding-y-lg * 2) !default;
+$input-height-lg:                       calc(#{$input-height-inner-lg} + #{$input-height-border}) !default;
+
+$input-transition:                      border-color .15s ease-in-out, box-shadow .15s ease-in-out !default;
+
+$form-text-margin-top:                  .25rem !default;
+
+$form-check-input-gutter:               1.25rem !default;
+$form-check-input-margin-y:             .3rem !default;
+$form-check-input-margin-x:             .25rem !default;
+
+$form-check-inline-margin-x:            .75rem !default;
+$form-check-inline-input-margin-x:      .3125rem !default;
+
+$form-group-margin-bottom:              1rem !default;
+
+$input-group-addon-color:               $input-color !default;
+$input-group-addon-bg:                  $gray-200 !default;
+$input-group-addon-border-color:        $input-border-color !default;
+
+$custom-forms-transition:               background-color .15s ease-in-out, border-color .15s ease-in-out, box-shadow .15s ease-in-out !default;
+
+$custom-control-gutter:                 1.5rem !default;
+$custom-control-spacer-x:               1rem !default;
+
+$custom-control-indicator-size:         1rem !default;
+$custom-control-indicator-bg:           $gray-300 !default;
+$custom-control-indicator-bg-size:      50% 50% !default;
+$custom-control-indicator-box-shadow:   inset 0 .25rem .25rem rgba($black, .1) !default;
+
+$custom-control-indicator-disabled-bg:          $gray-200 !default;
+$custom-control-label-disabled-color:           $gray-600 !default;
+
+$custom-control-indicator-checked-color:        $component-active-color !default;
+$custom-control-indicator-checked-bg:           $component-active-bg !default;
+$custom-control-indicator-checked-disabled-bg:  rgba(theme-color("primary"), .5) !default;
+$custom-control-indicator-checked-box-shadow:   none !default;
+
+$custom-control-indicator-focus-box-shadow:     0 0 0 1px $body-bg, $input-btn-focus-box-shadow !default;
+
+$custom-control-indicator-active-color:         $component-active-color !default;
+$custom-control-indicator-active-bg:            lighten($component-active-bg, 35%) !default;
+$custom-control-indicator-active-box-shadow:    none !default;
+
+$custom-checkbox-indicator-border-radius:       $border-radius !default;
+$custom-checkbox-indicator-icon-checked:        str-replace(url("data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 8 8'%3E%3Cpath fill='#{$custom-control-indicator-checked-color}' d='M6.564.75l-3.59 3.612-1.538-1.55L0 4.26 2.974 7.25 8 2.193z'/%3E%3C/svg%3E"), "#", "%23") !default;
+
+$custom-checkbox-indicator-indeterminate-bg:          $component-active-bg !default;
+$custom-checkbox-indicator-indeterminate-color:       $custom-control-indicator-checked-color !default;
+$custom-checkbox-indicator-icon-indeterminate:        str-replace(url("data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 4 4'%3E%3Cpath stroke='#{$custom-checkbox-indicator-indeterminate-color}' d='M0 2h4'/%3E%3C/svg%3E"), "#", "%23") !default;
+$custom-checkbox-indicator-indeterminate-box-shadow:  none !default;
+
+$custom-radio-indicator-border-radius:          50% !default;
+$custom-radio-indicator-icon-checked:           str-replace(url("data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='-4 -4 8 8'%3E%3Ccircle r='3' fill='#{$custom-control-indicator-checked-color}'/%3E%3C/svg%3E"), "#", "%23") !default;
+
+$custom-select-padding-y:           .375rem !default;
+$custom-select-padding-x:           .75rem !default;
+$custom-select-height:              $input-height !default;
+$custom-select-indicator-padding:   1rem !default; // Extra padding to account for the presence of the background-image based indicator
+$custom-select-line-height:         $input-btn-line-height !default;
+$custom-select-color:               $input-color !default;
+$custom-select-disabled-color:      $gray-600 !default;
+$custom-select-bg:                  $input-bg !default;
+$custom-select-disabled-bg:         $gray-200 !default;
+$custom-select-bg-size:             8px 10px !default; // In pixels because image dimensions
+$custom-select-indicator-color:     $gray-800 !default;
+$custom-select-indicator:           str-replace(url("data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 4 5'%3E%3Cpath fill='#{$custom-select-indicator-color}' d='M2 0L0 2h4zm0 5L0 3h4z'/%3E%3C/svg%3E"), "#", "%23") !default;
+$custom-select-border-width:        $input-btn-border-width !default;
+$custom-select-border-color:        $input-border-color !default;
+$custom-select-border-radius:       $border-radius !default;
+$custom-select-box-shadow:          inset 0 1px 2px rgba($black, .075) !default;
+
+$custom-select-focus-border-color:  $input-focus-border-color !default;
+$custom-select-focus-width:         $input-btn-focus-width !default;
+$custom-select-focus-box-shadow:    0 0 0 $custom-select-focus-width rgba($custom-select-focus-border-color, .5) !default;
+
+$custom-select-font-size-sm:        75% !default;
+$custom-select-height-sm:           $input-height-sm !default;
+
+$custom-select-font-size-lg:        125% !default;
+$custom-select-height-lg:           $input-height-lg !default;
+
+$custom-range-track-width:          100% !default;
+$custom-range-track-height:         .5rem !default;
+$custom-range-track-cursor:         pointer !default;
+$custom-range-track-bg:             $gray-300 !default;
+$custom-range-track-border-radius:  1rem !default;
+$custom-range-track-box-shadow:     inset 0 .25rem .25rem rgba($black, .1) !default;
+
+$custom-range-thumb-width:                   1rem !default;
+$custom-range-thumb-height:                  $custom-range-thumb-width !default;
+$custom-range-thumb-bg:                      $component-active-bg !default;
+$custom-range-thumb-border:                  0 !default;
+$custom-range-thumb-border-radius:           1rem !default;
+$custom-range-thumb-box-shadow:              0 .1rem .25rem rgba($black, .1) !default;
+$custom-range-thumb-focus-box-shadow:        0 0 0 1px $body-bg, $input-btn-focus-box-shadow !default;
+$custom-range-thumb-focus-box-shadow-width:  $input-btn-focus-width !default; // For focus box shadow issue in IE/Edge
+$custom-range-thumb-active-bg:               lighten($component-active-bg, 35%) !default;
+
+$custom-file-height:                $input-height !default;
+$custom-file-height-inner:          $input-height-inner !default;
+$custom-file-focus-border-color:    $input-focus-border-color !default;
+$custom-file-focus-box-shadow:      $input-btn-focus-box-shadow !default;
+$custom-file-disabled-bg:           $input-disabled-bg !default;
+
+$custom-file-padding-y:             $input-btn-padding-y !default;
+$custom-file-padding-x:             $input-btn-padding-x !default;
+$custom-file-line-height:           $input-btn-line-height !default;
+$custom-file-color:                 $input-color !default;
+$custom-file-bg:                    $input-bg !default;
+$custom-file-border-width:          $input-btn-border-width !default;
+$custom-file-border-color:          $input-border-color !default;
+$custom-file-border-radius:         $input-border-radius !default;
+$custom-file-box-shadow:            $input-box-shadow !default;
+$custom-file-button-color:          $custom-file-color !default;
+$custom-file-button-bg:             $input-group-addon-bg !default;
+$custom-file-text: (
+  en: "Browse"
+) !default;
+
+
+// Form validation
+$form-feedback-margin-top:          $form-text-margin-top !default;
+$form-feedback-font-size:           $small-font-size !default;
+$form-feedback-valid-color:         theme-color("success") !default;
+$form-feedback-invalid-color:       theme-color("danger") !default;
+
+
+// Dropdowns
+//
+// Dropdown menu container and contents.
+
+$dropdown-min-width:                10rem !default;
+$dropdown-padding-y:                .5rem !default;
+$dropdown-spacer:                   .125rem !default;
+$dropdown-bg:                       $white !default;
+$dropdown-border-color:             rgba($black, .15) !default;
+$dropdown-border-radius:            $border-radius !default;
+$dropdown-border-width:             $border-width !default;
+$dropdown-divider-bg:               $gray-200 !default;
+$dropdown-box-shadow:               0 .5rem 1rem rgba($black, .175) !default;
+
+$dropdown-link-color:               $gray-900 !default;
+$dropdown-link-hover-color:         darken($gray-900, 5%) !default;
+$dropdown-link-hover-bg:            $gray-100 !default;
+
+$dropdown-link-active-color:        $component-active-color !default;
+$dropdown-link-active-bg:           $component-active-bg !default;
+
+$dropdown-link-disabled-color:      $gray-600 !default;
+
+$dropdown-item-padding-y:           .25rem !default;
+$dropdown-item-padding-x:           1.5rem !default;
+
+$dropdown-header-color:             $gray-600 !default;
+
+
+// Z-index master list
+//
+// Warning: Avoid customizing these values. They're used for a bird's eye view
+// of components dependent on the z-axis and are designed to all work together.
+
+$zindex-dropdown:                   1000 !default;
+$zindex-sticky:                     1020 !default;
+$zindex-fixed:                      1030 !default;
+$zindex-modal-backdrop:             1040 !default;
+$zindex-modal:                      1050 !default;
+$zindex-popover:                    1060 !default;
+$zindex-tooltip:                    1070 !default;
+
+// Navs
+
+$nav-link-padding-y:                .5rem !default;
+$nav-link-padding-x:                1rem !default;
+$nav-link-disabled-color:           $gray-600 !default;
+
+$nav-tabs-border-color:             $gray-300 !default;
+$nav-tabs-border-width:             $border-width !default;
+$nav-tabs-border-radius:            $border-radius !default;
+$nav-tabs-link-hover-border-color:  $gray-200 $gray-200 $nav-tabs-border-color !default;
+$nav-tabs-link-active-color:        $gray-700 !default;
+$nav-tabs-link-active-bg:           $body-bg !default;
+$nav-tabs-link-active-border-color: $gray-300 $gray-300 $nav-tabs-link-active-bg !default;
+
+$nav-pills-border-radius:           $border-radius !default;
+$nav-pills-link-active-color:       $component-active-color !default;
+$nav-pills-link-active-bg:          $component-active-bg !default;
+
+$nav-divider-color:                 $gray-200 !default;
+$nav-divider-margin-y:              ($spacer / 2) !default;
+
+// Navbar
+
+$navbar-padding-y:                  ($spacer / 2) !default;
+$navbar-padding-x:                  $spacer !default;
+
+$navbar-nav-link-padding-x:         .5rem !default;
+
+$navbar-brand-font-size:            $font-size-lg !default;
+// Compute the navbar-brand padding-y so the navbar-brand will have the same height as navbar-text and nav-link
+$nav-link-height:                   ($font-size-base * $line-height-base + $nav-link-padding-y * 2) !default;
+$navbar-brand-height:               $navbar-brand-font-size * $line-height-base !default;
+$navbar-brand-padding-y:            ($nav-link-height - $navbar-brand-height) / 2 !default;
+
+$navbar-toggler-padding-y:          .25rem !default;
+$navbar-toggler-padding-x:          .75rem !default;
+$navbar-toggler-font-size:          $font-size-lg !default;
+$navbar-toggler-border-radius:      $btn-border-radius !default;
+
+$navbar-dark-color:                 rgba($white, .5) !default;
+$navbar-dark-hover-color:           rgba($white, .75) !default;
+$navbar-dark-active-color:          $white !default;
+$navbar-dark-disabled-color:        rgba($white, .25) !default;
+$navbar-dark-toggler-icon-bg:       str-replace(url("data:image/svg+xml;charset=utf8,%3Csvg viewBox='0 0 30 30' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath stroke='#{$navbar-dark-color}' stroke-width='2' stroke-linecap='round' stroke-miterlimit='10' d='M4 7h22M4 15h22M4 23h22'/%3E%3C/svg%3E"), "#", "%23") !default;
+$navbar-dark-toggler-border-color:  rgba($white, .1) !default;
+
+$navbar-light-color:                rgba($black, .5) !default;
+$navbar-light-hover-color:          rgba($black, .7) !default;
+$navbar-light-active-color:         rgba($black, .9) !default;
+$navbar-light-disabled-color:       rgba($black, .3) !default;
+$navbar-light-toggler-icon-bg:      str-replace(url("data:image/svg+xml;charset=utf8,%3Csvg viewBox='0 0 30 30' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath stroke='#{$navbar-light-color}' stroke-width='2' stroke-linecap='round' stroke-miterlimit='10' d='M4 7h22M4 15h22M4 23h22'/%3E%3C/svg%3E"), "#", "%23") !default;
+$navbar-light-toggler-border-color: rgba($black, .1) !default;
+
+// Pagination
+
+$pagination-padding-y:              .5rem !default;
+$pagination-padding-x:              .75rem !default;
+$pagination-padding-y-sm:           .25rem !default;
+$pagination-padding-x-sm:           .5rem !default;
+$pagination-padding-y-lg:           .75rem !default;
+$pagination-padding-x-lg:           1.5rem !default;
+$pagination-line-height:            1.25 !default;
+
+$pagination-color:                  $link-color !default;
+$pagination-bg:                     $white !default;
+$pagination-border-width:           $border-width !default;
+$pagination-border-color:           $gray-300 !default;
+
+$pagination-focus-box-shadow:       $input-btn-focus-box-shadow !default;
+$pagination-focus-outline:          0 !default;
+
+$pagination-hover-color:            $link-hover-color !default;
+$pagination-hover-bg:               $gray-200 !default;
+$pagination-hover-border-color:     $gray-300 !default;
+
+$pagination-active-color:           $component-active-color !default;
+$pagination-active-bg:              $component-active-bg !default;
+$pagination-active-border-color:    $pagination-active-bg !default;
+
+$pagination-disabled-color:         $gray-600 !default;
+$pagination-disabled-bg:            $white !default;
+$pagination-disabled-border-color:  $gray-300 !default;
+
+
+// Jumbotron
+
+$jumbotron-padding:                 2rem !default;
+$jumbotron-bg:                      $gray-200 !default;
+
+
+// Cards
+
+$card-spacer-y:                     .75rem !default;
+$card-spacer-x:                     1.25rem !default;
+$card-border-width:                 $border-width !default;
+$card-border-radius:                $border-radius !default;
+$card-border-color:                 rgba($black, .125) !default;
+$card-inner-border-radius:          calc(#{$card-border-radius} - #{$card-border-width}) !default;
+$card-cap-bg:                       rgba($black, .03) !default;
+$card-bg:                           $white !default;
+
+$card-img-overlay-padding:          1.25rem !default;
+
+$card-group-margin:                 ($grid-gutter-width / 2) !default;
+$card-deck-margin:                  $card-group-margin !default;
+
+$card-columns-count:                3 !default;
+$card-columns-gap:                  1.25rem !default;
+$card-columns-margin:               $card-spacer-y !default;
+
+
+// Tooltips
+
+$tooltip-font-size:                 $font-size-sm !default;
+$tooltip-max-width:                 200px !default;
+$tooltip-color:                     $white !default;
+$tooltip-bg:                        $black !default;
+$tooltip-border-radius:             $border-radius !default;
+$tooltip-opacity:                   .9 !default;
+$tooltip-padding-y:                 .25rem !default;
+$tooltip-padding-x:                 .5rem !default;
+$tooltip-margin:                    0 !default;
+
+$tooltip-arrow-width:               .8rem !default;
+$tooltip-arrow-height:              .4rem !default;
+$tooltip-arrow-color:               $tooltip-bg !default;
+
+
+// Popovers
+
+$popover-font-size:                 $font-size-sm !default;
+$popover-bg:                        $white !default;
+$popover-max-width:                 276px !default;
+$popover-border-width:              $border-width !default;
+$popover-border-color:              rgba($black, .2) !default;
+$popover-border-radius:             $border-radius-lg !default;
+$popover-box-shadow:                0 .25rem .5rem rgba($black, .2) !default;
+
+$popover-header-bg:                 darken($popover-bg, 3%) !default;
+$popover-header-color:              $headings-color !default;
+$popover-header-padding-y:          .5rem !default;
+$popover-header-padding-x:          .75rem !default;
+
+$popover-body-color:                $body-color !default;
+$popover-body-padding-y:            $popover-header-padding-y !default;
+$popover-body-padding-x:            $popover-header-padding-x !default;
+
+$popover-arrow-width:               1rem !default;
+$popover-arrow-height:              .5rem !default;
+$popover-arrow-color:               $popover-bg !default;
+
+$popover-arrow-outer-color:         fade-in($popover-border-color, .05) !default;
+
+
+// Badges
+
+$badge-font-size:                   75% !default;
+$badge-font-weight:                 $font-weight-bold !default;
+$badge-padding-y:                   .25em !default;
+$badge-padding-x:                   .4em !default;
+$badge-border-radius:               $border-radius !default;
+
+$badge-pill-padding-x:              .6em !default;
+// Use a higher than normal value to ensure completely rounded edges when
+// customizing padding or font-size on labels.
+$badge-pill-border-radius:          10rem !default;
+
+
+// Modals
+
+// Padding applied to the modal body
+$modal-inner-padding:               1rem !default;
+
+$modal-dialog-margin:               .5rem !default;
+$modal-dialog-margin-y-sm-up:       1.75rem !default;
+
+$modal-title-line-height:           $line-height-base !default;
+
+$modal-content-bg:                  $white !default;
+$modal-content-border-color:        rgba($black, .2) !default;
+$modal-content-border-width:        $border-width !default;
+$modal-content-border-radius:       $border-radius-lg !default;
+$modal-content-box-shadow-xs:       0 .25rem .5rem rgba($black, .5) !default;
+$modal-content-box-shadow-sm-up:    0 .5rem 1rem rgba($black, .5) !default;
+
+$modal-backdrop-bg:                 $black !default;
+$modal-backdrop-opacity:            .5 !default;
+$modal-header-border-color:         $gray-200 !default;
+$modal-footer-border-color:         $modal-header-border-color !default;
+$modal-header-border-width:         $modal-content-border-width !default;
+$modal-footer-border-width:         $modal-header-border-width !default;
+$modal-header-padding:              1rem !default;
+
+$modal-lg:                          800px !default;
+$modal-md:                          500px !default;
+$modal-sm:                          300px !default;
+
+$modal-transition:                  transform .3s ease-out !default;
+
+
+// Alerts
+//
+// Define alert colors, border radius, and padding.
+
+$alert-padding-y:                   .75rem !default;
+$alert-padding-x:                   1.25rem !default;
+$alert-margin-bottom:               1rem !default;
+$alert-border-radius:               $border-radius !default;
+$alert-link-font-weight:            $font-weight-bold !default;
+$alert-border-width:                $border-width !default;
+
+$alert-bg-level:                    -10 !default;
+$alert-border-level:                -9 !default;
+$alert-color-level:                 6 !default;
+
+
+// Progress bars
+
+$progress-height:                   1rem !default;
+$progress-font-size:                ($font-size-base * .75) !default;
+$progress-bg:                       $gray-200 !default;
+$progress-border-radius:            $border-radius !default;
+$progress-box-shadow:               inset 0 .1rem .1rem rgba($black, .1) !default;
+$progress-bar-color:                $white !default;
+$progress-bar-bg:                   theme-color("primary") !default;
+$progress-bar-animation-timing:     1s linear infinite !default;
+$progress-bar-transition:           width .6s ease !default;
+
+// List group
+
+$list-group-bg:                     $white !default;
+$list-group-border-color:           rgba($black, .125) !default;
+$list-group-border-width:           $border-width !default;
+$list-group-border-radius:          $border-radius !default;
+
+$list-group-item-padding-y:         .75rem !default;
+$list-group-item-padding-x:         1.25rem !default;
+
+$list-group-hover-bg:               $gray-100 !default;
+$list-group-active-color:           $component-active-color !default;
+$list-group-active-bg:              $component-active-bg !default;
+$list-group-active-border-color:    $list-group-active-bg !default;
+
+$list-group-disabled-color:         $gray-600 !default;
+$list-group-disabled-bg:            $list-group-bg !default;
+
+$list-group-action-color:           $gray-700 !default;
+$list-group-action-hover-color:     $list-group-action-color !default;
+
+$list-group-action-active-color:    $body-color !default;
+$list-group-action-active-bg:       $gray-200 !default;
+
+
+// Image thumbnails
+
+$thumbnail-padding:                 .25rem !default;
+$thumbnail-bg:                      $body-bg !default;
+$thumbnail-border-width:            $border-width !default;
+$thumbnail-border-color:            $gray-300 !default;
+$thumbnail-border-radius:           $border-radius !default;
+$thumbnail-box-shadow:              0 1px 2px rgba($black, .075) !default;
+
+
+// Figures
+
+$figure-caption-font-size:          90% !default;
+$figure-caption-color:              $gray-600 !default;
+
+
+// Breadcrumbs
+
+$breadcrumb-padding-y:              .75rem !default;
+$breadcrumb-padding-x:              1rem !default;
+$breadcrumb-item-padding:           .5rem !default;
+
+$breadcrumb-margin-bottom:          1rem !default;
+
+$breadcrumb-bg:                     $gray-200 !default;
+$breadcrumb-divider-color:          $gray-600 !default;
+$breadcrumb-active-color:           $gray-600 !default;
+$breadcrumb-divider:                quote("/") !default;
+
+$breadcrumb-border-radius:          $border-radius !default;
+
+
+// Carousel
+
+$carousel-control-color:            $white !default;
+$carousel-control-width:            15% !default;
+$carousel-control-opacity:          .5 !default;
+
+$carousel-indicator-width:          30px !default;
+$carousel-indicator-height:         3px !default;
+$carousel-indicator-spacer:         3px !default;
+$carousel-indicator-active-bg:      $white !default;
+
+$carousel-caption-width:            70% !default;
+$carousel-caption-color:            $white !default;
+
+$carousel-control-icon-width:       20px !default;
+
+$carousel-control-prev-icon-bg:     str-replace(url("data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='#{$carousel-control-color}' viewBox='0 0 8 8'%3E%3Cpath d='M5.25 0l-4 4 4 4 1.5-1.5-2.5-2.5 2.5-2.5-1.5-1.5z'/%3E%3C/svg%3E"), "#", "%23") !default;
+$carousel-control-next-icon-bg:     str-replace(url("data:image/svg+xml;charset=utf8,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='#{$carousel-control-color}' viewBox='0 0 8 8'%3E%3Cpath d='M2.75 0l-1.5 1.5 2.5 2.5-2.5 2.5 1.5 1.5 4-4-4-4z'/%3E%3C/svg%3E"), "#", "%23") !default;
+
+$carousel-transition:               transform .6s ease !default; // Define transform transition first if using multiple transitions (e.g., `transform 2s ease, opacity .5s ease-out`)
+
+
+// Close
+
+$close-font-size:                   $font-size-base * 1.5 !default;
+$close-font-weight:                 $font-weight-bold !default;
+$close-color:                       $black !default;
+$close-text-shadow:                 0 1px 0 $white !default;
+
+// Code
+
+$code-font-size:                    87.5% !default;
+$code-color:                        $pink !default;
+
+$kbd-padding-y:                     .2rem !default;
+$kbd-padding-x:                     .4rem !default;
+$kbd-font-size:                     $code-font-size !default;
+$kbd-color:                         $white !default;
+$kbd-bg:                            $gray-900 !default;
+
+$pre-color:                         $gray-900 !default;
+$pre-scrollable-max-height:         340px !default;
+
+
+// Printing
+$print-page-size:                   a3 !default;
+$print-body-min-width:              map-get($grid-breakpoints, "lg") !default;
diff --git a/src/sass/bootstrap4/bootstrap-grid.scss b/src/sass/bootstrap4/bootstrap-grid.scss
new file mode 100644
index 0000000..509171d
--- /dev/null
+++ b/src/sass/bootstrap4/bootstrap-grid.scss
@@ -0,0 +1,32 @@
+/*!
+ * Bootstrap Grid v4.1.3 (https://getbootstrap.com/)
+ * Copyright 2011-2018 The Bootstrap Authors
+ * Copyright 2011-2018 Twitter, Inc.
+ * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
+ */
+
+@at-root {
+  @-ms-viewport { width: device-width; } // stylelint-disable-line at-rule-no-vendor-prefix
+}
+
+html {
+  box-sizing: border-box;
+  -ms-overflow-style: scrollbar;
+}
+
+*,
+*::before,
+*::after {
+  box-sizing: inherit;
+}
+
+@import "functions";
+@import "variables";
+
+@import "mixins/breakpoints";
+@import "mixins/grid-framework";
+@import "mixins/grid";
+
+@import "grid";
+@import "utilities/display";
+@import "utilities/flex";
diff --git a/src/sass/bootstrap4/bootstrap-reboot.scss b/src/sass/bootstrap4/bootstrap-reboot.scss
new file mode 100644
index 0000000..75baeb7
--- /dev/null
+++ b/src/sass/bootstrap4/bootstrap-reboot.scss
@@ -0,0 +1,12 @@
+/*!
+ * Bootstrap Reboot v4.1.3 (https://getbootstrap.com/)
+ * Copyright 2011-2018 The Bootstrap Authors
+ * Copyright 2011-2018 Twitter, Inc.
+ * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
+ * Forked from Normalize.css, licensed MIT (https://github.com/necolas/normalize.css/blob/master/LICENSE.md)
+ */
+
+@import "functions";
+@import "variables";
+@import "mixins";
+@import "reboot";
diff --git a/src/sass/bootstrap4/bootstrap.scss b/src/sass/bootstrap4/bootstrap.scss
new file mode 100644
index 0000000..e3f7654
--- /dev/null
+++ b/src/sass/bootstrap4/bootstrap.scss
@@ -0,0 +1,42 @@
+/*!
+ * Bootstrap v4.1.3 (https://getbootstrap.com/)
+ * Copyright 2011-2018 The Bootstrap Authors
+ * Copyright 2011-2018 Twitter, Inc.
+ * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
+ */
+
+@import "functions";
+@import "variables";
+@import "mixins";
+@import "root";
+@import "reboot";
+@import "type";
+@import "images";
+@import "code";
+@import "grid";
+@import "tables";
+@import "forms";
+@import "buttons";
+@import "transitions";
+@import "dropdown";
+@import "button-group";
+@import "input-group";
+@import "custom-forms";
+@import "nav";
+@import "navbar";
+@import "card";
+@import "breadcrumb";
+@import "pagination";
+@import "badge";
+@import "jumbotron";
+@import "alert";
+@import "progress";
+@import "media";
+@import "list-group";
+@import "close";
+@import "modal";
+@import "tooltip";
+@import "popover";
+@import "carousel";
+@import "utilities";
+@import "print";
diff --git a/src/sass/bootstrap4/mixins/_alert.scss b/src/sass/bootstrap4/mixins/_alert.scss
new file mode 100644
index 0000000..db5a7eb
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_alert.scss
@@ -0,0 +1,13 @@
+@mixin alert-variant($background, $border, $color) {
+  color: $color;
+  @include gradient-bg($background);
+  border-color: $border;
+
+  hr {
+    border-top-color: darken($border, 5%);
+  }
+
+  .alert-link {
+    color: darken($color, 10%);
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_background-variant.scss b/src/sass/bootstrap4/mixins/_background-variant.scss
new file mode 100644
index 0000000..494439d
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_background-variant.scss
@@ -0,0 +1,21 @@
+// stylelint-disable declaration-no-important
+
+// Contextual backgrounds
+
+@mixin bg-variant($parent, $color) {
+  #{$parent} {
+    background-color: $color !important;
+  }
+  a#{$parent},
+  button#{$parent} {
+    @include hover-focus {
+      background-color: darken($color, 10%) !important;
+    }
+  }
+}
+
+@mixin bg-gradient-variant($parent, $color) {
+  #{$parent} {
+    background: $color linear-gradient(180deg, mix($body-bg, $color, 15%), $color) repeat-x !important;
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_badge.scss b/src/sass/bootstrap4/mixins/_badge.scss
new file mode 100644
index 0000000..eeca0b4
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_badge.scss
@@ -0,0 +1,12 @@
+@mixin badge-variant($bg) {
+  color: color-yiq($bg);
+  background-color: $bg;
+
+  &[href] {
+    @include hover-focus {
+      color: color-yiq($bg);
+      text-decoration: none;
+      background-color: darken($bg, 10%);
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_border-radius.scss b/src/sass/bootstrap4/mixins/_border-radius.scss
new file mode 100644
index 0000000..2024feb
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_border-radius.scss
@@ -0,0 +1,35 @@
+// Single side border-radius
+
+@mixin border-radius($radius: $border-radius) {
+  @if $enable-rounded {
+    border-radius: $radius;
+  }
+}
+
+@mixin border-top-radius($radius) {
+  @if $enable-rounded {
+    border-top-left-radius: $radius;
+    border-top-right-radius: $radius;
+  }
+}
+
+@mixin border-right-radius($radius) {
+  @if $enable-rounded {
+    border-top-right-radius: $radius;
+    border-bottom-right-radius: $radius;
+  }
+}
+
+@mixin border-bottom-radius($radius) {
+  @if $enable-rounded {
+    border-bottom-right-radius: $radius;
+    border-bottom-left-radius: $radius;
+  }
+}
+
+@mixin border-left-radius($radius) {
+  @if $enable-rounded {
+    border-top-left-radius: $radius;
+    border-bottom-left-radius: $radius;
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_box-shadow.scss b/src/sass/bootstrap4/mixins/_box-shadow.scss
new file mode 100644
index 0000000..b2410e5
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_box-shadow.scss
@@ -0,0 +1,5 @@
+@mixin box-shadow($shadow...) {
+  @if $enable-shadows {
+    box-shadow: $shadow;
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_breakpoints.scss b/src/sass/bootstrap4/mixins/_breakpoints.scss
new file mode 100644
index 0000000..59f25a2
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_breakpoints.scss
@@ -0,0 +1,123 @@
+// Breakpoint viewport sizes and media queries.
+//
+// Breakpoints are defined as a map of (name: minimum width), order from small to large:
+//
+//    (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px)
+//
+// The map defined in the `$grid-breakpoints` global variable is used as the `$breakpoints` argument by default.
+
+// Name of the next breakpoint, or null for the last breakpoint.
+//
+//    >> breakpoint-next(sm)
+//    md
+//    >> breakpoint-next(sm, (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px))
+//    md
+//    >> breakpoint-next(sm, $breakpoint-names: (xs sm md lg xl))
+//    md
+@function breakpoint-next($name, $breakpoints: $grid-breakpoints, $breakpoint-names: map-keys($breakpoints)) {
+  $n: index($breakpoint-names, $name);
+  @return if($n < length($breakpoint-names), nth($breakpoint-names, $n + 1), null);
+}
+
+// Minimum breakpoint width. Null for the smallest (first) breakpoint.
+//
+//    >> breakpoint-min(sm, (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px))
+//    576px
+@function breakpoint-min($name, $breakpoints: $grid-breakpoints) {
+  $min: map-get($breakpoints, $name);
+  @return if($min != 0, $min, null);
+}
+
+// Maximum breakpoint width. Null for the largest (last) breakpoint.
+// The maximum value is calculated as the minimum of the next one less 0.02px
+// to work around the limitations of `min-` and `max-` prefixes and viewports with fractional widths.
+// See https://www.w3.org/TR/mediaqueries-4/#mq-min-max
+// Uses 0.02px rather than 0.01px to work around a current rounding bug in Safari.
+// See https://bugs.webkit.org/show_bug.cgi?id=178261
+//
+//    >> breakpoint-max(sm, (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px))
+//    767.98px
+@function breakpoint-max($name, $breakpoints: $grid-breakpoints) {
+  $next: breakpoint-next($name, $breakpoints);
+  @return if($next, breakpoint-min($next, $breakpoints) - .02px, null);
+}
+
+// Returns a blank string if smallest breakpoint, otherwise returns the name with a dash in front.
+// Useful for making responsive utilities.
+//
+//    >> breakpoint-infix(xs, (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px))
+//    ""  (Returns a blank string)
+//    >> breakpoint-infix(sm, (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px))
+//    "-sm"
+@function breakpoint-infix($name, $breakpoints: $grid-breakpoints) {
+  @return if(breakpoint-min($name, $breakpoints) == null, "", "-#{$name}");
+}
+
+// Media of at least the minimum breakpoint width. No query for the smallest breakpoint.
+// Makes the @content apply to the given breakpoint and wider.
+@mixin media-breakpoint-up($name, $breakpoints: $grid-breakpoints) {
+  $min: breakpoint-min($name, $breakpoints);
+  @if $min {
+    @media (min-width: $min) {
+      @content;
+    }
+  } @else {
+    @content;
+  }
+}
+
+// Media of at most the maximum breakpoint width. No query for the largest breakpoint.
+// Makes the @content apply to the given breakpoint and narrower.
+@mixin media-breakpoint-down($name, $breakpoints: $grid-breakpoints) {
+  $max: breakpoint-max($name, $breakpoints);
+  @if $max {
+    @media (max-width: $max) {
+      @content;
+    }
+  } @else {
+    @content;
+  }
+}
+
+// Media that spans multiple breakpoint widths.
+// Makes the @content apply between the min and max breakpoints
+@mixin media-breakpoint-between($lower, $upper, $breakpoints: $grid-breakpoints) {
+  $min: breakpoint-min($lower, $breakpoints);
+  $max: breakpoint-max($upper, $breakpoints);
+
+  @if $min != null and $max != null {
+    @media (min-width: $min) and (max-width: $max) {
+      @content;
+    }
+  } @else if $max == null {
+    @include media-breakpoint-up($lower, $breakpoints) {
+      @content;
+    }
+  } @else if $min == null {
+    @include media-breakpoint-down($upper, $breakpoints) {
+      @content;
+    }
+  }
+}
+
+// Media between the breakpoint's minimum and maximum widths.
+// No minimum for the smallest breakpoint, and no maximum for the largest one.
+// Makes the @content apply only to the given breakpoint, not viewports any wider or narrower.
+@mixin media-breakpoint-only($name, $breakpoints: $grid-breakpoints) {
+  $min: breakpoint-min($name, $breakpoints);
+  $max: breakpoint-max($name, $breakpoints);
+
+  @if $min != null and $max != null {
+    @media (min-width: $min) and (max-width: $max) {
+      @content;
+    }
+  } @else if $max == null {
+    @include media-breakpoint-up($name, $breakpoints) {
+      @content;
+    }
+  } @else if $min == null {
+    @include media-breakpoint-down($name, $breakpoints) {
+      @content;
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_buttons.scss b/src/sass/bootstrap4/mixins/_buttons.scss
new file mode 100644
index 0000000..06ad677
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_buttons.scss
@@ -0,0 +1,109 @@
+// Button variants
+//
+// Easily pump out default styles, as well as :hover, :focus, :active,
+// and disabled options for all buttons
+
+@mixin button-variant($background, $border, $hover-background: darken($background, 7.5%), $hover-border: darken($border, 10%), $active-background: darken($background, 10%), $active-border: darken($border, 12.5%)) {
+  color: color-yiq($background);
+  @include gradient-bg($background);
+  border-color: $border;
+  @include box-shadow($btn-box-shadow);
+
+  @include hover {
+    color: color-yiq($hover-background);
+    @include gradient-bg($hover-background);
+    border-color: $hover-border;
+  }
+
+  &:focus,
+  &.focus {
+    // Avoid using mixin so we can pass custom focus shadow properly
+    @if $enable-shadows {
+      box-shadow: $btn-box-shadow, 0 0 0 $btn-focus-width rgba($border, .5);
+    } @else {
+      box-shadow: 0 0 0 $btn-focus-width rgba($border, .5);
+    }
+  }
+
+  // Disabled comes first so active can properly restyle
+  &.disabled,
+  &:disabled {
+    color: color-yiq($background);
+    background-color: $background;
+    border-color: $border;
+  }
+
+  &:not(:disabled):not(.disabled):active,
+  &:not(:disabled):not(.disabled).active,
+  .show > &.dropdown-toggle {
+    color: color-yiq($active-background);
+    background-color: $active-background;
+    @if $enable-gradients {
+      background-image: none; // Remove the gradient for the pressed/active state
+    }
+    border-color: $active-border;
+
+    &:focus {
+      // Avoid using mixin so we can pass custom focus shadow properly
+      @if $enable-shadows {
+        box-shadow: $btn-active-box-shadow, 0 0 0 $btn-focus-width rgba($border, .5);
+      } @else {
+        box-shadow: 0 0 0 $btn-focus-width rgba($border, .5);
+      }
+    }
+  }
+}
+
+@mixin button-outline-variant($color, $color-hover: color-yiq($color), $active-background: $color, $active-border: $color) {
+  color: $color;
+  background-color: transparent;
+  background-image: none;
+  border-color: $color;
+
+  &:hover {
+    color: $color-hover;
+    background-color: $active-background;
+    border-color: $active-border;
+  }
+
+  &:focus,
+  &.focus {
+    box-shadow: 0 0 0 $btn-focus-width rgba($color, .5);
+  }
+
+  &.disabled,
+  &:disabled {
+    color: $color;
+    background-color: transparent;
+  }
+
+  &:not(:disabled):not(.disabled):active,
+  &:not(:disabled):not(.disabled).active,
+  .show > &.dropdown-toggle {
+    color: color-yiq($active-background);
+    background-color: $active-background;
+    border-color: $active-border;
+
+    &:focus {
+      // Avoid using mixin so we can pass custom focus shadow properly
+      @if $enable-shadows and $btn-active-box-shadow != none {
+        box-shadow: $btn-active-box-shadow, 0 0 0 $btn-focus-width rgba($color, .5);
+      } @else {
+        box-shadow: 0 0 0 $btn-focus-width rgba($color, .5);
+      }
+    }
+  }
+}
+
+// Button sizes
+@mixin button-size($padding-y, $padding-x, $font-size, $line-height, $border-radius) {
+  padding: $padding-y $padding-x;
+  font-size: $font-size;
+  line-height: $line-height;
+  // Manually declare to provide an override to the browser default
+  @if $enable-rounded {
+    border-radius: $border-radius;
+  } @else {
+    border-radius: 0;
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_caret.scss b/src/sass/bootstrap4/mixins/_caret.scss
new file mode 100644
index 0000000..82aea42
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_caret.scss
@@ -0,0 +1,66 @@
+@mixin caret-down {
+  border-top: $caret-width solid;
+  border-right: $caret-width solid transparent;
+  border-bottom: 0;
+  border-left: $caret-width solid transparent;
+}
+
+@mixin caret-up {
+  border-top: 0;
+  border-right: $caret-width solid transparent;
+  border-bottom: $caret-width solid;
+  border-left: $caret-width solid transparent;
+}
+
+@mixin caret-right {
+  border-top: $caret-width solid transparent;
+  border-right: 0;
+  border-bottom: $caret-width solid transparent;
+  border-left: $caret-width solid;
+}
+
+@mixin caret-left {
+  border-top: $caret-width solid transparent;
+  border-right: $caret-width solid;
+  border-bottom: $caret-width solid transparent;
+}
+
+@mixin caret($direction: down) {
+  @if $enable-caret {
+    &::after {
+      display: inline-block;
+      width: 0;
+      height: 0;
+      margin-left: $caret-width * .85;
+      vertical-align: $caret-width * .85;
+      content: "";
+      @if $direction == down {
+        @include caret-down;
+      } @else if $direction == up {
+        @include caret-up;
+      } @else if $direction == right {
+        @include caret-right;
+      }
+    }
+
+    @if $direction == left {
+      &::after {
+        display: none;
+      }
+
+      &::before {
+        display: inline-block;
+        width: 0;
+        height: 0;
+        margin-right: $caret-width * .85;
+        vertical-align: $caret-width * .85;
+        content: "";
+        @include caret-left;
+      }
+    }
+
+    &:empty::after {
+      margin-left: 0;
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_clearfix.scss b/src/sass/bootstrap4/mixins/_clearfix.scss
new file mode 100644
index 0000000..11a977b
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_clearfix.scss
@@ -0,0 +1,7 @@
+@mixin clearfix() {
+  &::after {
+    display: block;
+    clear: both;
+    content: "";
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_float.scss b/src/sass/bootstrap4/mixins/_float.scss
new file mode 100644
index 0000000..48fa8b6
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_float.scss
@@ -0,0 +1,11 @@
+// stylelint-disable declaration-no-important
+
+@mixin float-left {
+  float: left !important;
+}
+@mixin float-right {
+  float: right !important;
+}
+@mixin float-none {
+  float: none !important;
+}
diff --git a/src/sass/bootstrap4/mixins/_forms.scss b/src/sass/bootstrap4/mixins/_forms.scss
new file mode 100644
index 0000000..3a61878
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_forms.scss
@@ -0,0 +1,147 @@
+// Form control focus state
+//
+// Generate a customized focus state and for any input with the specified color,
+// which defaults to the `$input-focus-border-color` variable.
+//
+// We highly encourage you to not customize the default value, but instead use
+// this to tweak colors on an as-needed basis. This aesthetic change is based on
+// WebKit's default styles, but applicable to a wider range of browsers. Its
+// usability and accessibility should be taken into account with any change.
+//
+// Example usage: change the default blue border and shadow to white for better
+// contrast against a dark gray background.
+@mixin form-control-focus() {
+  &:focus {
+    color: $input-focus-color;
+    background-color: $input-focus-bg;
+    border-color: $input-focus-border-color;
+    outline: 0;
+    // Avoid using mixin so we can pass custom focus shadow properly
+    @if $enable-shadows {
+      box-shadow: $input-box-shadow, $input-focus-box-shadow;
+    } @else {
+      box-shadow: $input-focus-box-shadow;
+    }
+  }
+}
+
+
+@mixin form-validation-state($state, $color) {
+  .#{$state}-feedback {
+    display: none;
+    width: 100%;
+    margin-top: $form-feedback-margin-top;
+    font-size: $form-feedback-font-size;
+    color: $color;
+  }
+
+  .#{$state}-tooltip {
+    position: absolute;
+    top: 100%;
+    z-index: 5;
+    display: none;
+    max-width: 100%; // Contain to parent when possible
+    padding: $tooltip-padding-y $tooltip-padding-x;
+    margin-top: .1rem;
+    font-size: $tooltip-font-size;
+    line-height: $line-height-base;
+    color: color-yiq($color);
+    background-color: rgba($color, $tooltip-opacity);
+    @include border-radius($tooltip-border-radius);
+  }
+
+  .form-control,
+  .custom-select {
+    .was-validated &:#{$state},
+    &.is-#{$state} {
+      border-color: $color;
+
+      &:focus {
+        border-color: $color;
+        box-shadow: 0 0 0 $input-focus-width rgba($color, .25);
+      }
+
+      ~ .#{$state}-feedback,
+      ~ .#{$state}-tooltip {
+        display: block;
+      }
+    }
+  }
+
+  .form-control-file {
+    .was-validated &:#{$state},
+    &.is-#{$state} {
+      ~ .#{$state}-feedback,
+      ~ .#{$state}-tooltip {
+        display: block;
+      }
+    }
+  }
+
+  .form-check-input {
+    .was-validated &:#{$state},
+    &.is-#{$state} {
+      ~ .form-check-label {
+        color: $color;
+      }
+
+      ~ .#{$state}-feedback,
+      ~ .#{$state}-tooltip {
+        display: block;
+      }
+    }
+  }
+
+  .custom-control-input {
+    .was-validated &:#{$state},
+    &.is-#{$state} {
+      ~ .custom-control-label {
+        color: $color;
+
+        &::before {
+          background-color: lighten($color, 25%);
+        }
+      }
+
+      ~ .#{$state}-feedback,
+      ~ .#{$state}-tooltip {
+        display: block;
+      }
+
+      &:checked {
+        ~ .custom-control-label::before {
+          @include gradient-bg(lighten($color, 10%));
+        }
+      }
+
+      &:focus {
+        ~ .custom-control-label::before {
+          box-shadow: 0 0 0 1px $body-bg, 0 0 0 $input-focus-width rgba($color, .25);
+        }
+      }
+    }
+  }
+
+  // custom file
+  .custom-file-input {
+    .was-validated &:#{$state},
+    &.is-#{$state} {
+      ~ .custom-file-label {
+        border-color: $color;
+
+        &::after { border-color: inherit; }
+      }
+
+      ~ .#{$state}-feedback,
+      ~ .#{$state}-tooltip {
+        display: block;
+      }
+
+      &:focus {
+        ~ .custom-file-label {
+          box-shadow: 0 0 0 $input-focus-width rgba($color, .25);
+        }
+      }
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_gradients.scss b/src/sass/bootstrap4/mixins/_gradients.scss
new file mode 100644
index 0000000..88c4d64
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_gradients.scss
@@ -0,0 +1,45 @@
+// Gradients
+
+@mixin gradient-bg($color) {
+  @if $enable-gradients {
+    background: $color linear-gradient(180deg, mix($body-bg, $color, 15%), $color) repeat-x;
+  } @else {
+    background-color: $color;
+  }
+}
+
+// Horizontal gradient, from left to right
+//
+// Creates two color stops, start and end, by specifying a color and position for each color stop.
+@mixin gradient-x($start-color: $gray-700, $end-color: $gray-800, $start-percent: 0%, $end-percent: 100%) {
+  background-image: linear-gradient(to right, $start-color $start-percent, $end-color $end-percent);
+  background-repeat: repeat-x;
+}
+
+// Vertical gradient, from top to bottom
+//
+// Creates two color stops, start and end, by specifying a color and position for each color stop.
+@mixin gradient-y($start-color: $gray-700, $end-color: $gray-800, $start-percent: 0%, $end-percent: 100%) {
+  background-image: linear-gradient(to bottom, $start-color $start-percent, $end-color $end-percent);
+  background-repeat: repeat-x;
+}
+
+@mixin gradient-directional($start-color: $gray-700, $end-color: $gray-800, $deg: 45deg) {
+  background-image: linear-gradient($deg, $start-color, $end-color);
+  background-repeat: repeat-x;
+}
+@mixin gradient-x-three-colors($start-color: $blue, $mid-color: $purple, $color-stop: 50%, $end-color: $red) {
+  background-image: linear-gradient(to right, $start-color, $mid-color $color-stop, $end-color);
+  background-repeat: no-repeat;
+}
+@mixin gradient-y-three-colors($start-color: $blue, $mid-color: $purple, $color-stop: 50%, $end-color: $red) {
+  background-image: linear-gradient($start-color, $mid-color $color-stop, $end-color);
+  background-repeat: no-repeat;
+}
+@mixin gradient-radial($inner-color: $gray-700, $outer-color: $gray-800) {
+  background-image: radial-gradient(circle, $inner-color, $outer-color);
+  background-repeat: no-repeat;
+}
+@mixin gradient-striped($color: rgba($white, .15), $angle: 45deg) {
+  background-image: linear-gradient($angle, $color 25%, transparent 25%, transparent 50%, $color 50%, $color 75%, transparent 75%, transparent);
+}
diff --git a/src/sass/bootstrap4/mixins/_grid-framework.scss b/src/sass/bootstrap4/mixins/_grid-framework.scss
new file mode 100644
index 0000000..7b37f86
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_grid-framework.scss
@@ -0,0 +1,67 @@
+// Framework grid generation
+//
+// Used only by Bootstrap to generate the correct number of grid classes given
+// any value of `$grid-columns`.
+
+@mixin make-grid-columns($columns: $grid-columns, $gutter: $grid-gutter-width, $breakpoints: $grid-breakpoints) {
+  // Common properties for all breakpoints
+  %grid-column {
+    position: relative;
+    width: 100%;
+    min-height: 1px; // Prevent columns from collapsing when empty
+    padding-right: ($gutter / 2);
+    padding-left: ($gutter / 2);
+  }
+
+  @each $breakpoint in map-keys($breakpoints) {
+    $infix: breakpoint-infix($breakpoint, $breakpoints);
+
+    // Allow columns to stretch full width below their breakpoints
+    @for $i from 1 through $columns {
+      .col#{$infix}-#{$i} {
+        @extend %grid-column;
+      }
+    }
+    .col#{$infix},
+    .col#{$infix}-auto {
+      @extend %grid-column;
+    }
+
+    @include media-breakpoint-up($breakpoint, $breakpoints) {
+      // Provide basic `.col-{bp}` classes for equal-width flexbox columns
+      .col#{$infix} {
+        flex-basis: 0;
+        flex-grow: 1;
+        max-width: 100%;
+      }
+      .col#{$infix}-auto {
+        flex: 0 0 auto;
+        width: auto;
+        max-width: none; // Reset earlier grid tiers
+      }
+
+      @for $i from 1 through $columns {
+        .col#{$infix}-#{$i} {
+          @include make-col($i, $columns);
+        }
+      }
+
+      .order#{$infix}-first { order: -1; }
+
+      .order#{$infix}-last { order: $columns + 1; }
+
+      @for $i from 0 through $columns {
+        .order#{$infix}-#{$i} { order: $i; }
+      }
+
+      // `$columns - 1` because offsetting by the width of an entire row isn't possible
+      @for $i from 0 through ($columns - 1) {
+        @if not ($infix == "" and $i == 0) { // Avoid emitting useless .offset-0
+          .offset#{$infix}-#{$i} {
+            @include make-col-offset($i, $columns);
+          }
+        }
+      }
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_grid.scss b/src/sass/bootstrap4/mixins/_grid.scss
new file mode 100644
index 0000000..b75ebcb
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_grid.scss
@@ -0,0 +1,52 @@
+/// Grid system
+//
+// Generate semantic grid columns with these mixins.
+
+@mixin make-container() {
+  width: 100%;
+  padding-right: ($grid-gutter-width / 2);
+  padding-left: ($grid-gutter-width / 2);
+  margin-right: auto;
+  margin-left: auto;
+}
+
+
+// For each breakpoint, define the maximum width of the container in a media query
+@mixin make-container-max-widths($max-widths: $container-max-widths, $breakpoints: $grid-breakpoints) {
+  @each $breakpoint, $container-max-width in $max-widths {
+    @include media-breakpoint-up($breakpoint, $breakpoints) {
+      max-width: $container-max-width;
+    }
+  }
+}
+
+@mixin make-row() {
+  display: flex;
+  flex-wrap: wrap;
+  margin-right: ($grid-gutter-width / -2);
+  margin-left: ($grid-gutter-width / -2);
+}
+
+@mixin make-col-ready() {
+  position: relative;
+  // Prevent columns from becoming too narrow when at smaller grid tiers by
+  // always setting `width: 100%;`. This works because we use `flex` values
+  // later on to override this initial width.
+  width: 100%;
+  min-height: 1px; // Prevent collapsing
+  padding-right: ($grid-gutter-width / 2);
+  padding-left: ($grid-gutter-width / 2);
+}
+
+@mixin make-col($size, $columns: $grid-columns) {
+  flex: 0 0 percentage($size / $columns);
+  // Add a `max-width` to ensure content within each column does not blow out
+  // the width of the column. Applies to IE10+ and Firefox. Chrome and Safari
+  // do not appear to require this.
+  max-width: percentage($size / $columns);
+}
+
+@mixin make-col-offset($size, $columns: $grid-columns) {
+  $num: $size / $columns;
+  margin-left: if($num == 0, 0, percentage($num));
+}
diff --git a/src/sass/bootstrap4/mixins/_hover.scss b/src/sass/bootstrap4/mixins/_hover.scss
new file mode 100644
index 0000000..192f847
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_hover.scss
@@ -0,0 +1,37 @@
+// Hover mixin and `$enable-hover-media-query` are deprecated.
+//
+// Originally added during our alphas and maintained during betas, this mixin was
+// designed to prevent `:hover` stickiness on iOS-an issue where hover styles
+// would persist after initial touch.
+//
+// For backward compatibility, we've kept these mixins and updated them to
+// always return their regular pseudo-classes instead of a shimmed media query.
+//
+// Issue: https://github.com/twbs/bootstrap/issues/25195
+
+@mixin hover {
+  &:hover { @content; }
+}
+
+@mixin hover-focus {
+  &:hover,
+  &:focus {
+    @content;
+  }
+}
+
+@mixin plain-hover-focus {
+  &,
+  &:hover,
+  &:focus {
+    @content;
+  }
+}
+
+@mixin hover-focus-active {
+  &:hover,
+  &:focus,
+  &:active {
+    @content;
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_image.scss b/src/sass/bootstrap4/mixins/_image.scss
new file mode 100644
index 0000000..0544f0d
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_image.scss
@@ -0,0 +1,36 @@
+// Image Mixins
+// - Responsive image
+// - Retina image
+
+
+// Responsive image
+//
+// Keep images from scaling beyond the width of their parents.
+
+@mixin img-fluid {
+  // Part 1: Set a maximum relative to the parent
+  max-width: 100%;
+  // Part 2: Override the height to auto, otherwise images will be stretched
+  // when setting a width and height attribute on the img element.
+  height: auto;
+}
+
+
+// Retina image
+//
+// Short retina mixin for setting background-image and -size.
+
+// stylelint-disable indentation, media-query-list-comma-newline-after
+@mixin img-retina($file-1x, $file-2x, $width-1x, $height-1x) {
+  background-image: url($file-1x);
+
+  // Autoprefixer takes care of adding -webkit-min-device-pixel-ratio and -o-min-device-pixel-ratio,
+  // but doesn't convert dppx=>dpi.
+  // There's no such thing as unprefixed min-device-pixel-ratio since it's nonstandard.
+  // Compatibility info: https://caniuse.com/#feat=css-media-resolution
+  @media only screen and (min-resolution: 192dpi), // IE9-11 don't support dppx
+  only screen and (min-resolution: 2dppx) { // Standardized
+    background-image: url($file-2x);
+    background-size: $width-1x $height-1x;
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_list-group.scss b/src/sass/bootstrap4/mixins/_list-group.scss
new file mode 100644
index 0000000..cd47a4e
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_list-group.scss
@@ -0,0 +1,21 @@
+// List Groups
+
+@mixin list-group-item-variant($state, $background, $color) {
+  .list-group-item-#{$state} {
+    color: $color;
+    background-color: $background;
+
+    &.list-group-item-action {
+      @include hover-focus {
+        color: $color;
+        background-color: darken($background, 5%);
+      }
+
+      &.active {
+        color: $white;
+        background-color: $color;
+        border-color: $color;
+      }
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_lists.scss b/src/sass/bootstrap4/mixins/_lists.scss
new file mode 100644
index 0000000..2518562
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_lists.scss
@@ -0,0 +1,7 @@
+// Lists
+
+// Unstyled keeps list items block level, just removes default browser padding and list-style
+@mixin list-unstyled {
+  padding-left: 0;
+  list-style: none;
+}
diff --git a/src/sass/bootstrap4/mixins/_nav-divider.scss b/src/sass/bootstrap4/mixins/_nav-divider.scss
new file mode 100644
index 0000000..4fb37b6
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_nav-divider.scss
@@ -0,0 +1,10 @@
+// Horizontal dividers
+//
+// Dividers (basically an hr) within dropdowns and nav lists
+
+@mixin nav-divider($color: $nav-divider-color, $margin-y: $nav-divider-margin-y) {
+  height: 0;
+  margin: $margin-y 0;
+  overflow: hidden;
+  border-top: 1px solid $color;
+}
diff --git a/src/sass/bootstrap4/mixins/_pagination.scss b/src/sass/bootstrap4/mixins/_pagination.scss
new file mode 100644
index 0000000..ff36eb6
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_pagination.scss
@@ -0,0 +1,22 @@
+// Pagination
+
+@mixin pagination-size($padding-y, $padding-x, $font-size, $line-height, $border-radius) {
+  .page-link {
+    padding: $padding-y $padding-x;
+    font-size: $font-size;
+    line-height: $line-height;
+  }
+
+  .page-item {
+    &:first-child {
+      .page-link {
+        @include border-left-radius($border-radius);
+      }
+    }
+    &:last-child {
+      .page-link {
+        @include border-right-radius($border-radius);
+      }
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_reset-text.scss b/src/sass/bootstrap4/mixins/_reset-text.scss
new file mode 100644
index 0000000..71edb00
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_reset-text.scss
@@ -0,0 +1,17 @@
+@mixin reset-text {
+  font-family: $font-family-base;
+  // We deliberately do NOT reset font-size or word-wrap.
+  font-style: normal;
+  font-weight: $font-weight-normal;
+  line-height: $line-height-base;
+  text-align: left; // Fallback for where `start` is not supported
+  text-align: start; // stylelint-disable-line declaration-block-no-duplicate-properties
+  text-decoration: none;
+  text-shadow: none;
+  text-transform: none;
+  letter-spacing: normal;
+  word-break: normal;
+  word-spacing: normal;
+  white-space: normal;
+  line-break: auto;
+}
diff --git a/src/sass/bootstrap4/mixins/_resize.scss b/src/sass/bootstrap4/mixins/_resize.scss
new file mode 100644
index 0000000..66f233a
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_resize.scss
@@ -0,0 +1,6 @@
+// Resize anything
+
+@mixin resizable($direction) {
+  overflow: auto; // Per CSS3 UI, `resize` only applies when `overflow` isn't `visible`
+  resize: $direction; // Options: horizontal, vertical, both
+}
diff --git a/src/sass/bootstrap4/mixins/_screen-reader.scss b/src/sass/bootstrap4/mixins/_screen-reader.scss
new file mode 100644
index 0000000..812591b
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_screen-reader.scss
@@ -0,0 +1,33 @@
+// Only display content to screen readers
+//
+// See: https://a11yproject.com/posts/how-to-hide-content/
+// See: https://hugogiraudel.com/2016/10/13/css-hide-and-seek/
+
+@mixin sr-only {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  padding: 0;
+  overflow: hidden;
+  clip: rect(0, 0, 0, 0);
+  white-space: nowrap;
+  border: 0;
+}
+
+// Use in conjunction with .sr-only to only display content when it's focused.
+//
+// Useful for "Skip to main content" links; see https://www.w3.org/TR/2013/NOTE-WCAG20-TECHS-20130905/G1
+//
+// Credit: HTML5 Boilerplate
+
+@mixin sr-only-focusable {
+  &:active,
+  &:focus {
+    position: static;
+    width: auto;
+    height: auto;
+    overflow: visible;
+    clip: auto;
+    white-space: normal;
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_size.scss b/src/sass/bootstrap4/mixins/_size.scss
new file mode 100644
index 0000000..b9dd48e
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_size.scss
@@ -0,0 +1,6 @@
+// Sizing shortcuts
+
+@mixin size($width, $height: $width) {
+  width: $width;
+  height: $height;
+}
diff --git a/src/sass/bootstrap4/mixins/_table-row.scss b/src/sass/bootstrap4/mixins/_table-row.scss
new file mode 100644
index 0000000..84f1d30
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_table-row.scss
@@ -0,0 +1,30 @@
+// Tables
+
+@mixin table-row-variant($state, $background) {
+  // Exact selectors below required to override `.table-striped` and prevent
+  // inheritance to nested tables.
+  .table-#{$state} {
+    &,
+    > th,
+    > td {
+      background-color: $background;
+    }
+  }
+
+  // Hover states for `.table-hover`
+  // Note: this is not available for cells or rows within `thead` or `tfoot`.
+  .table-hover {
+    $hover-background: darken($background, 5%);
+
+    .table-#{$state} {
+      @include hover {
+        background-color: $hover-background;
+
+        > td,
+        > th {
+          background-color: $hover-background;
+        }
+      }
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_text-emphasis.scss b/src/sass/bootstrap4/mixins/_text-emphasis.scss
new file mode 100644
index 0000000..58db3e0
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_text-emphasis.scss
@@ -0,0 +1,14 @@
+// stylelint-disable declaration-no-important
+
+// Typography
+
+@mixin text-emphasis-variant($parent, $color) {
+  #{$parent} {
+    color: $color !important;
+  }
+  a#{$parent} {
+    @include hover-focus {
+      color: darken($color, 10%) !important;
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_text-hide.scss b/src/sass/bootstrap4/mixins/_text-hide.scss
new file mode 100644
index 0000000..9ffab16
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_text-hide.scss
@@ -0,0 +1,13 @@
+// CSS image replacement
+@mixin text-hide($ignore-warning: false) {
+  // stylelint-disable-next-line font-family-no-missing-generic-family-keyword
+  font: 0/0 a;
+  color: transparent;
+  text-shadow: none;
+  background-color: transparent;
+  border: 0;
+
+  @if ($ignore-warning != true) {
+    @warn "The `text-hide()` mixin has been deprecated as of v4.1.0. It will be removed entirely in v5.";
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_text-truncate.scss b/src/sass/bootstrap4/mixins/_text-truncate.scss
new file mode 100644
index 0000000..3504bb1
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_text-truncate.scss
@@ -0,0 +1,8 @@
+// Text truncate
+// Requires inline-block or block for proper styling
+
+@mixin text-truncate() {
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
diff --git a/src/sass/bootstrap4/mixins/_transition.scss b/src/sass/bootstrap4/mixins/_transition.scss
new file mode 100644
index 0000000..f853821
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_transition.scss
@@ -0,0 +1,13 @@
+@mixin transition($transition...) {
+  @if $enable-transitions {
+    @if length($transition) == 0 {
+      transition: $transition-base;
+    } @else {
+      transition: $transition;
+    }
+  }
+
+  @media screen and (prefers-reduced-motion: reduce) {
+    transition: none;
+  }
+}
diff --git a/src/sass/bootstrap4/mixins/_visibility.scss b/src/sass/bootstrap4/mixins/_visibility.scss
new file mode 100644
index 0000000..fe523d0
--- /dev/null
+++ b/src/sass/bootstrap4/mixins/_visibility.scss
@@ -0,0 +1,7 @@
+// stylelint-disable declaration-no-important
+
+// Visibility
+
+@mixin invisible($visibility) {
+  visibility: $visibility !important;
+}
diff --git a/src/sass/bootstrap4/utilities/_align.scss b/src/sass/bootstrap4/utilities/_align.scss
new file mode 100644
index 0000000..8b7df9f
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_align.scss
@@ -0,0 +1,8 @@
+// stylelint-disable declaration-no-important
+
+.align-baseline    { vertical-align: baseline !important; } // Browser default
+.align-top         { vertical-align: top !important; }
+.align-middle      { vertical-align: middle !important; }
+.align-bottom      { vertical-align: bottom !important; }
+.align-text-bottom { vertical-align: text-bottom !important; }
+.align-text-top    { vertical-align: text-top !important; }
diff --git a/src/sass/bootstrap4/utilities/_background.scss b/src/sass/bootstrap4/utilities/_background.scss
new file mode 100644
index 0000000..1f18b2f
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_background.scss
@@ -0,0 +1,19 @@
+// stylelint-disable declaration-no-important
+
+@each $color, $value in $theme-colors {
+  @include bg-variant(".bg-#{$color}", $value);
+}
+
+@if $enable-gradients {
+  @each $color, $value in $theme-colors {
+    @include bg-gradient-variant(".bg-gradient-#{$color}", $value);
+  }
+}
+
+.bg-white {
+  background-color: $white !important;
+}
+
+.bg-transparent {
+  background-color: transparent !important;
+}
diff --git a/src/sass/bootstrap4/utilities/_borders.scss b/src/sass/bootstrap4/utilities/_borders.scss
new file mode 100644
index 0000000..b8832ef
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_borders.scss
@@ -0,0 +1,59 @@
+// stylelint-disable declaration-no-important
+
+//
+// Border
+//
+
+.border         { border: $border-width solid $border-color !important; }
+.border-top     { border-top: $border-width solid $border-color !important; }
+.border-right   { border-right: $border-width solid $border-color !important; }
+.border-bottom  { border-bottom: $border-width solid $border-color !important; }
+.border-left    { border-left: $border-width solid $border-color !important; }
+
+.border-0        { border: 0 !important; }
+.border-top-0    { border-top: 0 !important; }
+.border-right-0  { border-right: 0 !important; }
+.border-bottom-0 { border-bottom: 0 !important; }
+.border-left-0   { border-left: 0 !important; }
+
+@each $color, $value in $theme-colors {
+  .border-#{$color} {
+    border-color: $value !important;
+  }
+}
+
+.border-white {
+  border-color: $white !important;
+}
+
+//
+// Border-radius
+//
+
+.rounded {
+  border-radius: $border-radius !important;
+}
+.rounded-top {
+  border-top-left-radius: $border-radius !important;
+  border-top-right-radius: $border-radius !important;
+}
+.rounded-right {
+  border-top-right-radius: $border-radius !important;
+  border-bottom-right-radius: $border-radius !important;
+}
+.rounded-bottom {
+  border-bottom-right-radius: $border-radius !important;
+  border-bottom-left-radius: $border-radius !important;
+}
+.rounded-left {
+  border-top-left-radius: $border-radius !important;
+  border-bottom-left-radius: $border-radius !important;
+}
+
+.rounded-circle {
+  border-radius: 50% !important;
+}
+
+.rounded-0 {
+  border-radius: 0 !important;
+}
diff --git a/src/sass/bootstrap4/utilities/_clearfix.scss b/src/sass/bootstrap4/utilities/_clearfix.scss
new file mode 100644
index 0000000..e92522a
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_clearfix.scss
@@ -0,0 +1,3 @@
+.clearfix {
+  @include clearfix();
+}
diff --git a/src/sass/bootstrap4/utilities/_display.scss b/src/sass/bootstrap4/utilities/_display.scss
new file mode 100644
index 0000000..20aeeb5
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_display.scss
@@ -0,0 +1,38 @@
+// stylelint-disable declaration-no-important
+
+//
+// Utilities for common `display` values
+//
+
+@each $breakpoint in map-keys($grid-breakpoints) {
+  @include media-breakpoint-up($breakpoint) {
+    $infix: breakpoint-infix($breakpoint, $grid-breakpoints);
+
+    .d#{$infix}-none         { display: none !important; }
+    .d#{$infix}-inline       { display: inline !important; }
+    .d#{$infix}-inline-block { display: inline-block !important; }
+    .d#{$infix}-block        { display: block !important; }
+    .d#{$infix}-table        { display: table !important; }
+    .d#{$infix}-table-row    { display: table-row !important; }
+    .d#{$infix}-table-cell   { display: table-cell !important; }
+    .d#{$infix}-flex         { display: flex !important; }
+    .d#{$infix}-inline-flex  { display: inline-flex !important; }
+  }
+}
+
+
+//
+// Utilities for toggling `display` in print
+//
+
+@media print {
+  .d-print-none         { display: none !important; }
+  .d-print-inline       { display: inline !important; }
+  .d-print-inline-block { display: inline-block !important; }
+  .d-print-block        { display: block !important; }
+  .d-print-table        { display: table !important; }
+  .d-print-table-row    { display: table-row !important; }
+  .d-print-table-cell   { display: table-cell !important; }
+  .d-print-flex         { display: flex !important; }
+  .d-print-inline-flex  { display: inline-flex !important; }
+}
diff --git a/src/sass/bootstrap4/utilities/_embed.scss b/src/sass/bootstrap4/utilities/_embed.scss
new file mode 100644
index 0000000..d3362b6
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_embed.scss
@@ -0,0 +1,52 @@
+// Credit: Nicolas Gallagher and SUIT CSS.
+
+.embed-responsive {
+  position: relative;
+  display: block;
+  width: 100%;
+  padding: 0;
+  overflow: hidden;
+
+  &::before {
+    display: block;
+    content: "";
+  }
+
+  .embed-responsive-item,
+  iframe,
+  embed,
+  object,
+  video {
+    position: absolute;
+    top: 0;
+    bottom: 0;
+    left: 0;
+    width: 100%;
+    height: 100%;
+    border: 0;
+  }
+}
+
+.embed-responsive-21by9 {
+  &::before {
+    padding-top: percentage(9 / 21);
+  }
+}
+
+.embed-responsive-16by9 {
+  &::before {
+    padding-top: percentage(9 / 16);
+  }
+}
+
+.embed-responsive-4by3 {
+  &::before {
+    padding-top: percentage(3 / 4);
+  }
+}
+
+.embed-responsive-1by1 {
+  &::before {
+    padding-top: percentage(1 / 1);
+  }
+}
diff --git a/src/sass/bootstrap4/utilities/_flex.scss b/src/sass/bootstrap4/utilities/_flex.scss
new file mode 100644
index 0000000..3d4266e
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_flex.scss
@@ -0,0 +1,51 @@
+// stylelint-disable declaration-no-important
+
+// Flex variation
+//
+// Custom styles for additional flex alignment options.
+
+@each $breakpoint in map-keys($grid-breakpoints) {
+  @include media-breakpoint-up($breakpoint) {
+    $infix: breakpoint-infix($breakpoint, $grid-breakpoints);
+
+    .flex#{$infix}-row            { flex-direction: row !important; }
+    .flex#{$infix}-column         { flex-direction: column !important; }
+    .flex#{$infix}-row-reverse    { flex-direction: row-reverse !important; }
+    .flex#{$infix}-column-reverse { flex-direction: column-reverse !important; }
+
+    .flex#{$infix}-wrap         { flex-wrap: wrap !important; }
+    .flex#{$infix}-nowrap       { flex-wrap: nowrap !important; }
+    .flex#{$infix}-wrap-reverse { flex-wrap: wrap-reverse !important; }
+    .flex#{$infix}-fill         { flex: 1 1 auto !important; }
+    .flex#{$infix}-grow-0       { flex-grow: 0 !important; }
+    .flex#{$infix}-grow-1       { flex-grow: 1 !important; }
+    .flex#{$infix}-shrink-0     { flex-shrink: 0 !important; }
+    .flex#{$infix}-shrink-1     { flex-shrink: 1 !important; }
+
+    .justify-content#{$infix}-start   { justify-content: flex-start !important; }
+    .justify-content#{$infix}-end     { justify-content: flex-end !important; }
+    .justify-content#{$infix}-center  { justify-content: center !important; }
+    .justify-content#{$infix}-between { justify-content: space-between !important; }
+    .justify-content#{$infix}-around  { justify-content: space-around !important; }
+
+    .align-items#{$infix}-start    { align-items: flex-start !important; }
+    .align-items#{$infix}-end      { align-items: flex-end !important; }
+    .align-items#{$infix}-center   { align-items: center !important; }
+    .align-items#{$infix}-baseline { align-items: baseline !important; }
+    .align-items#{$infix}-stretch  { align-items: stretch !important; }
+
+    .align-content#{$infix}-start   { align-content: flex-start !important; }
+    .align-content#{$infix}-end     { align-content: flex-end !important; }
+    .align-content#{$infix}-center  { align-content: center !important; }
+    .align-content#{$infix}-between { align-content: space-between !important; }
+    .align-content#{$infix}-around  { align-content: space-around !important; }
+    .align-content#{$infix}-stretch { align-content: stretch !important; }
+
+    .align-self#{$infix}-auto     { align-self: auto !important; }
+    .align-self#{$infix}-start    { align-self: flex-start !important; }
+    .align-self#{$infix}-end      { align-self: flex-end !important; }
+    .align-self#{$infix}-center   { align-self: center !important; }
+    .align-self#{$infix}-baseline { align-self: baseline !important; }
+    .align-self#{$infix}-stretch  { align-self: stretch !important; }
+  }
+}
diff --git a/src/sass/bootstrap4/utilities/_float.scss b/src/sass/bootstrap4/utilities/_float.scss
new file mode 100644
index 0000000..01655e9
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_float.scss
@@ -0,0 +1,9 @@
+@each $breakpoint in map-keys($grid-breakpoints) {
+  @include media-breakpoint-up($breakpoint) {
+    $infix: breakpoint-infix($breakpoint, $grid-breakpoints);
+
+    .float#{$infix}-left  { @include float-left; }
+    .float#{$infix}-right { @include float-right; }
+    .float#{$infix}-none  { @include float-none; }
+  }
+}
diff --git a/src/sass/bootstrap4/utilities/_position.scss b/src/sass/bootstrap4/utilities/_position.scss
new file mode 100644
index 0000000..9ecdeeb
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_position.scss
@@ -0,0 +1,37 @@
+// stylelint-disable declaration-no-important
+
+// Common values
+
+// Sass list not in variables since it's not intended for customization.
+// stylelint-disable-next-line scss/dollar-variable-default
+$positions: static, relative, absolute, fixed, sticky;
+
+@each $position in $positions {
+  .position-#{$position} { position: $position !important; }
+}
+
+// Shorthand
+
+.fixed-top {
+  position: fixed;
+  top: 0;
+  right: 0;
+  left: 0;
+  z-index: $zindex-fixed;
+}
+
+.fixed-bottom {
+  position: fixed;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  z-index: $zindex-fixed;
+}
+
+.sticky-top {
+  @supports (position: sticky) {
+    position: sticky;
+    top: 0;
+    z-index: $zindex-sticky;
+  }
+}
diff --git a/src/sass/bootstrap4/utilities/_screenreaders.scss b/src/sass/bootstrap4/utilities/_screenreaders.scss
new file mode 100644
index 0000000..9f26fde
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_screenreaders.scss
@@ -0,0 +1,11 @@
+//
+// Screenreaders
+//
+
+.sr-only {
+  @include sr-only();
+}
+
+.sr-only-focusable {
+  @include sr-only-focusable();
+}
diff --git a/src/sass/bootstrap4/utilities/_shadows.scss b/src/sass/bootstrap4/utilities/_shadows.scss
new file mode 100644
index 0000000..f5d03fc
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_shadows.scss
@@ -0,0 +1,6 @@
+// stylelint-disable declaration-no-important
+
+.shadow-sm { box-shadow: $box-shadow-sm !important; }
+.shadow { box-shadow: $box-shadow !important; }
+.shadow-lg { box-shadow: $box-shadow-lg !important; }
+.shadow-none { box-shadow: none !important; }
diff --git a/src/sass/bootstrap4/utilities/_sizing.scss b/src/sass/bootstrap4/utilities/_sizing.scss
new file mode 100644
index 0000000..e95a4db
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_sizing.scss
@@ -0,0 +1,12 @@
+// stylelint-disable declaration-no-important
+
+// Width and height
+
+@each $prop, $abbrev in (width: w, height: h) {
+  @each $size, $length in $sizes {
+    .#{$abbrev}-#{$size} { #{$prop}: $length !important; }
+  }
+}
+
+.mw-100 { max-width: 100% !important; }
+.mh-100 { max-height: 100% !important; }
diff --git a/src/sass/bootstrap4/utilities/_spacing.scss b/src/sass/bootstrap4/utilities/_spacing.scss
new file mode 100644
index 0000000..b2e2354
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_spacing.scss
@@ -0,0 +1,51 @@
+// stylelint-disable declaration-no-important
+
+// Margin and Padding
+
+@each $breakpoint in map-keys($grid-breakpoints) {
+  @include media-breakpoint-up($breakpoint) {
+    $infix: breakpoint-infix($breakpoint, $grid-breakpoints);
+
+    @each $prop, $abbrev in (margin: m, padding: p) {
+      @each $size, $length in $spacers {
+
+        .#{$abbrev}#{$infix}-#{$size} { #{$prop}: $length !important; }
+        .#{$abbrev}t#{$infix}-#{$size},
+        .#{$abbrev}y#{$infix}-#{$size} {
+          #{$prop}-top: $length !important;
+        }
+        .#{$abbrev}r#{$infix}-#{$size},
+        .#{$abbrev}x#{$infix}-#{$size} {
+          #{$prop}-right: $length !important;
+        }
+        .#{$abbrev}b#{$infix}-#{$size},
+        .#{$abbrev}y#{$infix}-#{$size} {
+          #{$prop}-bottom: $length !important;
+        }
+        .#{$abbrev}l#{$infix}-#{$size},
+        .#{$abbrev}x#{$infix}-#{$size} {
+          #{$prop}-left: $length !important;
+        }
+      }
+    }
+
+    // Some special margin utils
+    .m#{$infix}-auto { margin: auto !important; }
+    .mt#{$infix}-auto,
+    .my#{$infix}-auto {
+      margin-top: auto !important;
+    }
+    .mr#{$infix}-auto,
+    .mx#{$infix}-auto {
+      margin-right: auto !important;
+    }
+    .mb#{$infix}-auto,
+    .my#{$infix}-auto {
+      margin-bottom: auto !important;
+    }
+    .ml#{$infix}-auto,
+    .mx#{$infix}-auto {
+      margin-left: auto !important;
+    }
+  }
+}
diff --git a/src/sass/bootstrap4/utilities/_text.scss b/src/sass/bootstrap4/utilities/_text.scss
new file mode 100644
index 0000000..9d96c46
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_text.scss
@@ -0,0 +1,58 @@
+// stylelint-disable declaration-no-important
+
+//
+// Text
+//
+
+.text-monospace { font-family: $font-family-monospace; }
+
+// Alignment
+
+.text-justify  { text-align: justify !important; }
+.text-nowrap   { white-space: nowrap !important; }
+.text-truncate { @include text-truncate; }
+
+// Responsive alignment
+
+@each $breakpoint in map-keys($grid-breakpoints) {
+  @include media-breakpoint-up($breakpoint) {
+    $infix: breakpoint-infix($breakpoint, $grid-breakpoints);
+
+    .text#{$infix}-left   { text-align: left !important; }
+    .text#{$infix}-right  { text-align: right !important; }
+    .text#{$infix}-center { text-align: center !important; }
+  }
+}
+
+// Transformation
+
+.text-lowercase  { text-transform: lowercase !important; }
+.text-uppercase  { text-transform: uppercase !important; }
+.text-capitalize { text-transform: capitalize !important; }
+
+// Weight and italics
+
+.font-weight-light  { font-weight: $font-weight-light !important; }
+.font-weight-normal { font-weight: $font-weight-normal !important; }
+.font-weight-bold   { font-weight: $font-weight-bold !important; }
+.font-italic        { font-style: italic !important; }
+
+// Contextual colors
+
+.text-white { color: $white !important; }
+
+@each $color, $value in $theme-colors {
+  @include text-emphasis-variant(".text-#{$color}", $value);
+}
+
+.text-body { color: $body-color !important; }
+.text-muted { color: $text-muted !important; }
+
+.text-black-50 { color: rgba($black, .5) !important; }
+.text-white-50 { color: rgba($white, .5) !important; }
+
+// Misc
+
+.text-hide {
+  @include text-hide($ignore-warning: true);
+}
diff --git a/src/sass/bootstrap4/utilities/_visibility.scss b/src/sass/bootstrap4/utilities/_visibility.scss
new file mode 100644
index 0000000..823406d
--- /dev/null
+++ b/src/sass/bootstrap4/utilities/_visibility.scss
@@ -0,0 +1,11 @@
+//
+// Visibility utilities
+//
+
+.visible {
+  @include invisible(visible);
+}
+
+.invisible {
+  @include invisible(hidden);
+}
-- 
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