Merge branch 'v4-dev' into stretched-link

22 files changed, 194 insertions, 133 deletions

diff --git a/scss/_alert.scss b/scss/_alert.scss
index dd43e2376a..da2a98af94 100644
--- a/scss/_alert.scss
+++ b/scss/_alert.scss
@@ -27,7 +27,7 @@
 // Expand the right padding and account for the close button's positioning.
 
 .alert-dismissible {
-  padding-right: ($close-font-size + $alert-padding-x * 2);
+  padding-right: $close-font-size + $alert-padding-x * 2;
 
   // Adjust close link position
   .close {
diff --git a/scss/_badge.scss b/scss/_badge.scss
index bdbe4b9cc8..c727ba5a2b 100644
--- a/scss/_badge.scss
+++ b/scss/_badge.scss
@@ -13,6 +13,7 @@
   white-space: nowrap;
   vertical-align: baseline;
   @include border-radius($badge-border-radius);
+  @include transition($badge-transition);
 
   @at-root a#{&} {
     @include hover-focus {
diff --git a/scss/_card.scss b/scss/_card.scss
index f3de02708b..377bec0f1a 100644
--- a/scss/_card.scss
+++ b/scss/_card.scss
@@ -43,7 +43,7 @@
 }
 
 .card-subtitle {
-  margin-top: -($card-spacer-y / 2);
+  margin-top: -$card-spacer-y / 2;
   margin-bottom: 0;
 }
 
@@ -99,15 +99,15 @@
 //
 
 .card-header-tabs {
-  margin-right: -($card-spacer-x / 2);
+  margin-right: -$card-spacer-x / 2;
   margin-bottom: -$card-spacer-y;
-  margin-left: -($card-spacer-x / 2);
+  margin-left: -$card-spacer-x / 2;
   border-bottom: 0;
 }
 
 .card-header-pills {
-  margin-right: -($card-spacer-x / 2);
-  margin-left: -($card-spacer-x / 2);
+  margin-right: -$card-spacer-x / 2;
+  margin-left: -$card-spacer-x / 2;
 }
 
 // Card image
diff --git a/scss/_carousel.scss b/scss/_carousel.scss
index 3ba447e300..8e6639ac07 100644
--- a/scss/_carousel.scss
+++ b/scss/_carousel.scss
@@ -187,9 +187,9 @@
 
 .carousel-caption {
   position: absolute;
-  right: ((100% - $carousel-caption-width) / 2);
+  right: (100% - $carousel-caption-width) / 2;
   bottom: 20px;
-  left: ((100% - $carousel-caption-width) / 2);
+  left: (100% - $carousel-caption-width) / 2;
   z-index: 10;
   padding-top: 20px;
   padding-bottom: 20px;
diff --git a/scss/_custom-forms.scss b/scss/_custom-forms.scss
index e999daf0ca..e6bf7ad6f5 100644
--- a/scss/_custom-forms.scss
+++ b/scss/_custom-forms.scss
@@ -10,8 +10,8 @@
 .custom-control {
   position: relative;
   display: block;
-  min-height: ($font-size-base * $line-height-base);
-  padding-left: $custom-control-gutter;
+  min-height: $font-size-base * $line-height-base;
+  padding-left: $custom-control-gutter + $custom-control-indicator-size;
 }
 
 .custom-control-inline {
@@ -74,8 +74,8 @@
   // 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;
+    top: ($font-size-base * $line-height-base - $custom-control-indicator-size) / 2;
+    left: -($custom-control-gutter + $custom-control-indicator-size);
     display: block;
     width: $custom-control-indicator-size;
     height: $custom-control-indicator-size;
@@ -89,8 +89,8 @@
   // Foreground (icon)
   &::after {
     position: absolute;
-    top: (($font-size-base * $line-height-base - $custom-control-indicator-size) / 2);
-    left: -$custom-control-gutter;
+    top: ($font-size-base * $line-height-base - $custom-control-indicator-size) / 2;
+    left: -($custom-control-gutter + $custom-control-indicator-size);
     display: block;
     width: $custom-control-indicator-size;
     height: $custom-control-indicator-size;
@@ -161,6 +161,47 @@
 }
 
 
+// switches
+//
+// Tweak a few things for switches
+
+.custom-switch {
+  padding-left: $custom-switch-width + $custom-control-gutter;
+
+  .custom-control-label {
+    &::before {
+      left: -($custom-switch-width + $custom-control-gutter);
+      width: $custom-switch-width;
+      pointer-events: all;
+      border-radius: $custom-switch-indicator-border-radius;
+    }
+
+    &::after {
+      top: calc(#{(($font-size-base * $line-height-base - $custom-control-indicator-size) / 2)} + #{$custom-control-indicator-border-width * 2});
+      left: calc(#{-($custom-switch-width + $custom-control-gutter)} + #{$custom-control-indicator-border-width * 2});
+      width: $custom-switch-indicator-size;
+      height: $custom-switch-indicator-size;
+      background-color: $custom-control-indicator-border-color;
+      border-radius: $custom-switch-indicator-border-radius;
+      @include transition(transform .15s ease-in-out, $custom-forms-transition);
+    }
+  }
+
+  .custom-control-input:checked ~ .custom-control-label {
+    &::after {
+      background-color: $custom-control-indicator-bg;
+      transform: translateX($custom-switch-width - $custom-control-indicator-size);
+    }
+  }
+
+  .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
@@ -346,7 +387,7 @@
   &::-webkit-slider-thumb {
     width: $custom-range-thumb-width;
     height: $custom-range-thumb-height;
-    margin-top: (($custom-range-track-height - $custom-range-thumb-height) / 2); // Webkit specific
+    margin-top: ($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);
@@ -421,7 +462,7 @@
     cursor: $custom-range-track-cursor;
     background-color: transparent;
     border-color: transparent;
-    border-width: ($custom-range-thumb-height * .5);
+    border-width: $custom-range-thumb-height / 2;
     @include box-shadow($custom-range-track-box-shadow);
   }
 
diff --git a/scss/_dropdown.scss b/scss/_dropdown.scss
index 93c1d78e95..c6907c8a8c 100644
--- a/scss/_dropdown.scss
+++ b/scss/_dropdown.scss
@@ -118,7 +118,7 @@
 
 // Dividers (basically an `<hr>`) within the dropdown
 .dropdown-divider {
-  @include nav-divider($dropdown-divider-bg);
+  @include nav-divider($dropdown-divider-bg, $dropdown-divider-margin-y);
 }
 
 // Links, buttons, and more within the dropdown menu
diff --git a/scss/_forms.scss b/scss/_forms.scss
index a83e04d657..2db6d834cd 100644
--- a/scss/_forms.scss
+++ b/scss/_forms.scss
@@ -190,13 +190,13 @@ textarea.form-control {
 .form-row {
   display: flex;
   flex-wrap: wrap;
-  margin-right: -5px;
-  margin-left: -5px;
+  margin-right: -$form-grid-gutter-width / 2;
+  margin-left: -$form-grid-gutter-width / 2;
 
   > .col,
   > [class*="col-"] {
-    padding-right: 5px;
-    padding-left: 5px;
+    padding-right: $form-grid-gutter-width / 2;
+    padding-left: $form-grid-gutter-width / 2;
   }
 }
 
@@ -318,6 +318,7 @@ textarea.form-control {
     }
     .form-check-input {
       position: relative;
+      flex-shrink: 0;
       margin-top: 0;
       margin-right: $form-check-input-margin-x;
       margin-left: 0;
diff --git a/scss/_images.scss b/scss/_images.scss
index 2bce02f631..8e69b772f8 100644
--- a/scss/_images.scss
+++ b/scss/_images.scss
@@ -32,7 +32,7 @@
 }
 
 .figure-img {
-  margin-bottom: ($spacer / 2);
+  margin-bottom: $spacer / 2;
   line-height: 1;
 }
 
diff --git a/scss/_input-group.scss b/scss/_input-group.scss
index 6fb8c429b4..81b33077a6 100644
--- a/scss/_input-group.scss
+++ b/scss/_input-group.scss
@@ -163,7 +163,7 @@
 
 .input-group-lg > .custom-select,
 .input-group-sm > .custom-select {
-  padding-right: ($custom-select-padding-x + $custom-select-indicator-padding);
+  padding-right: $custom-select-padding-x + $custom-select-indicator-padding;
 }
 
 
diff --git a/scss/_popover.scss b/scss/_popover.scss
index 3ef5f628bd..e9a1ea8575 100644
--- a/scss/_popover.scss
+++ b/scss/_popover.scss
@@ -38,21 +38,21 @@
 .bs-popover-top {
   margin-bottom: $popover-arrow-height;
 
-  .arrow {
+  > .arrow {
     bottom: calc((#{$popover-arrow-height} + #{$popover-border-width}) * -1);
   }
 
-  .arrow::before,
-  .arrow::after {
+  > .arrow::before,
+  > .arrow::after {
     border-width: $popover-arrow-height ($popover-arrow-width / 2) 0;
   }
 
-  .arrow::before {
+  > .arrow::before {
     bottom: 0;
     border-top-color: $popover-arrow-outer-color;
   }
 
-  .arrow::after {
+  > .arrow::after {
     bottom: $popover-border-width;
     border-top-color: $popover-arrow-color;
   }
@@ -61,24 +61,24 @@
 .bs-popover-right {
   margin-left: $popover-arrow-height;
 
-  .arrow {
+  > .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 {
+  > .arrow::before,
+  > .arrow::after {
     border-width: ($popover-arrow-width / 2) $popover-arrow-height ($popover-arrow-width / 2) 0;
   }
 
-  .arrow::before {
+  > .arrow::before {
     left: 0;
     border-right-color: $popover-arrow-outer-color;
   }
 
-  .arrow::after {
+  > .arrow::after {
     left: $popover-border-width;
     border-right-color: $popover-arrow-color;
   }
@@ -87,21 +87,21 @@
 .bs-popover-bottom {
   margin-top: $popover-arrow-height;
 
-  .arrow {
+  > .arrow {
     top: calc((#{$popover-arrow-height} + #{$popover-border-width}) * -1);
   }
 
-  .arrow::before,
-  .arrow::after {
+  > .arrow::before,
+  > .arrow::after {
     border-width: 0 ($popover-arrow-width / 2) $popover-arrow-height ($popover-arrow-width / 2);
   }
 
-  .arrow::before {
+  > .arrow::before {
     top: 0;
     border-bottom-color: $popover-arrow-outer-color;
   }
 
-  .arrow::after {
+  > .arrow::after {
     top: $popover-border-width;
     border-bottom-color: $popover-arrow-color;
   }
@@ -113,7 +113,7 @@
     left: 50%;
     display: block;
     width: $popover-arrow-width;
-    margin-left: ($popover-arrow-width / -2);
+    margin-left: -$popover-arrow-width / 2;
     content: "";
     border-bottom: $popover-border-width solid $popover-header-bg;
   }
@@ -122,24 +122,24 @@
 .bs-popover-left {
   margin-right: $popover-arrow-height;
 
-  .arrow {
+  > .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 {
+  > .arrow::before,
+  > .arrow::after {
     border-width: ($popover-arrow-width / 2) 0 ($popover-arrow-width / 2) $popover-arrow-height;
   }
 
-  .arrow::before {
+  > .arrow::before {
     right: 0;
     border-left-color: $popover-arrow-outer-color;
   }
 
-  .arrow::after {
+  > .arrow::after {
     right: $popover-border-width;
     border-left-color: $popover-arrow-color;
   }
diff --git a/scss/_reboot.scss b/scss/_reboot.scss
index ed4821a4d4..d4167cc8ec 100644
--- a/scss/_reboot.scss
+++ b/scss/_reboot.scss
@@ -14,9 +14,7 @@
 // 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.
+// 5. Change the default tap highlight to be completely transparent in iOS.
 
 *,
 *::before,
@@ -28,15 +26,7 @@ html {
   font-family: sans-serif; // 2
   line-height: 1.15; // 3
   -webkit-text-size-adjust: 100%; // 4
-  -ms-overflow-style: scrollbar; // 5
-  -webkit-tap-highlight-color: rgba($black, 0); // 6
-}
-
-// IE10+ doesn't honor `<meta name="viewport">` in some cases.
-@at-root {
-  @-ms-viewport {
-    width: device-width;
-  }
+  -webkit-tap-highlight-color: rgba($black, 0); // 5
 }
 
 // Shim for "new" HTML5 structural elements to display correctly (IE10, older browsers)
@@ -161,7 +151,7 @@ blockquote {
 
 b,
 strong {
-  font-weight: bolder; // Add the correct font weight in Chrome, Edge, and Safari
+  font-weight: $font-weight-bolder; // Add the correct font weight in Chrome, Edge, and Safari
 }
 
 small {
@@ -240,9 +230,6 @@ pre {
   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;
 }
 
 
diff --git a/scss/_tables.scss b/scss/_tables.scss
index 92d4ec9b5b..7d66208397 100644
--- a/scss/_tables.scss
+++ b/scss/_tables.scss
@@ -5,6 +5,7 @@
 .table {
   width: 100%;
   margin-bottom: $spacer;
+  color: $table-color;
   background-color: $table-bg; // Reset for nesting within parents with `background-color`.
 
   th,
@@ -56,7 +57,7 @@
   thead {
     th,
     td {
-      border-bottom-width: (2 * $table-border-width);
+      border-bottom-width: 2 * $table-border-width;
     }
   }
 }
@@ -88,6 +89,7 @@
 .table-hover {
   tbody tr {
     @include hover {
+      color: $table-hover-color;
       background-color: $table-hover-bg;
     }
   }
@@ -152,6 +154,7 @@
   &.table-hover {
     tbody tr {
       @include hover {
+        color: $table-dark-hover-color;
         background-color: $table-dark-hover-bg;
       }
     }
diff --git a/scss/_toasts.scss b/scss/_toasts.scss
index d6ba4ca141..e77cdaec7d 100644
--- a/scss/_toasts.scss
+++ b/scss/_toasts.scss
@@ -1,21 +1,30 @@
 .toast {
-  display: none;
   max-width: $toast-max-width;
   overflow: hidden; // cheap rounded corners on nested items
   font-size: $toast-font-size; // knock it down to 14px
   background-color: $toast-background-color;
   background-clip: padding-box;
   border: $toast-border-width solid $toast-border-color;
-  border-radius: $toast-border-radius;
   box-shadow: $toast-box-shadow;
   backdrop-filter: blur(10px);
+  opacity: 0;
+  @include border-radius($toast-border-radius);
 
-  + .toast {
-    margin-top: $toast-padding-x;
+  &:not(:last-child) {
+    margin-bottom: $toast-padding-x;
+  }
+
+  &.showing {
+    opacity: 1;
   }
 
   &.show {
     display: block;
+    opacity: 1;
+  }
+
+  &.hide {
+    display: none;
   }
 }
 
diff --git a/scss/_variables.scss b/scss/_variables.scss
index 988624451b..26a2df81d6 100644
--- a/scss/_variables.scss
+++ b/scss/_variables.scss
@@ -166,7 +166,7 @@ $body-color:                $gray-900 !default;
 //
 // Style anchor elements.
 
-$link-color:                              $primary !default;
+$link-color:                              theme-color("primary") !default;
 $link-decoration:                         none !default;
 $link-hover-color:                        darken($link-color, 15%) !default;
 $link-hover-decoration:                   underline !default;
@@ -250,7 +250,7 @@ $box-shadow:                  0 .5rem 1rem rgba($black, .15) !default;
 $box-shadow-lg:               0 1rem 3rem rgba($black, .175) !default;
 
 $component-active-color:      $white !default;
-$component-active-bg:         $primary !default;
+$component-active-bg:         theme-color("primary") !default;
 
 $caret-width:                 .3em !default;
 
@@ -275,7 +275,7 @@ $embed-responsive-aspect-ratios: join(
 // Font, line-height, and color for body text, headings, and more.
 
 // stylelint-disable value-keyword-case
-$font-family-sans-serif:      -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, Noto Sans, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji" !default;
+$font-family-sans-serif:      -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", 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
@@ -300,7 +300,7 @@ $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-margin-bottom:      $spacer / 2 !default;
 $headings-font-family:        inherit !default;
 $headings-font-weight:        500 !default;
 $headings-line-height:        1.2 !default;
@@ -352,21 +352,25 @@ $hr-margin-y:                 $spacer !default;
 $table-cell-padding:          .75rem !default;
 $table-cell-padding-sm:       .3rem !default;
 
+$table-color:                 $body-color !default;
 $table-bg:                    transparent !default;
 $table-accent-bg:             rgba($black, .05) !default;
+$table-hover-color:           $table-color !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-border-color:          $border-color !default;
 
 $table-head-bg:               $gray-200 !default;
 $table-head-color:            $gray-700 !default;
 
-$table-dark-bg:               $gray-900 !default;
+$table-dark-color:            $white !default;
+$table-dark-bg:               $gray-800 !default;
 $table-dark-accent-bg:        rgba($white, .05) !default;
+$table-dark-hover-color:      $table-dark-color !default;
 $table-dark-hover-bg:         rgba($white, .075) !default;
-$table-dark-border-color:     lighten($gray-900, 7.5%) !default;
+$table-dark-border-color:     lighten($table-dark-bg, 7.5%) !default;
 $table-dark-color:            $white !default;
 
 $table-striped-order:         odd !default;
@@ -506,6 +510,7 @@ $form-check-input-margin-x:             .25rem !default;
 $form-check-inline-margin-x:            .75rem !default;
 $form-check-inline-input-margin-x:      .3125rem !default;
 
+$form-grid-gutter-width:                10px !default;
 $form-group-margin-bottom:              1rem !default;
 
 $input-group-addon-color:               $input-color !default;
@@ -514,7 +519,7 @@ $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-gutter:                 .5rem !default;
 $custom-control-spacer-x:               1rem !default;
 
 $custom-control-indicator-size:         1rem !default;
@@ -530,7 +535,7 @@ $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($primary, .5) !default;
+$custom-control-indicator-checked-disabled-bg:  rgba(theme-color("primary"), .5) !default;
 $custom-control-indicator-checked-box-shadow:   none !default;
 $custom-control-indicator-checked-border-color: $custom-control-indicator-checked-bg !default;
 
@@ -554,6 +559,10 @@ $custom-checkbox-indicator-indeterminate-border-color: $custom-checkbox-indicato
 $custom-radio-indicator-border-radius:          50% !default;
 $custom-radio-indicator-icon-checked:           str-replace(url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='-4 -4 8 8'%3e%3ccircle r='3' fill='#{$custom-control-indicator-checked-color}'/%3e%3c/svg%3e"), "#", "%23") !default;
 
+$custom-switch-width:                           $custom-control-indicator-size * 1.75 !default;
+$custom-switch-indicator-border-radius:         $custom-control-indicator-size / 2 !default;
+$custom-switch-indicator-size:                  calc(#{$custom-control-indicator-size} - #{$custom-control-indicator-border-width * 4}) !default;
+
 $custom-select-padding-y:           $input-btn-padding-y !default;
 $custom-select-padding-x:           $input-btn-padding-x !default;
 $custom-select-height:              $input-height !default;
@@ -637,8 +646,8 @@ $custom-file-text: (
 
 $form-feedback-margin-top:          $form-text-margin-top !default;
 $form-feedback-font-size:           $small-font-size !default;
-$form-feedback-valid-color:         $success !default;
-$form-feedback-invalid-color:       $danger !default;
+$form-feedback-valid-color:         theme-color("success") !default;
+$form-feedback-invalid-color:       theme-color("danger") !default;
 
 $form-feedback-icon-valid-color:    $form-feedback-valid-color !default;
 $form-feedback-icon-valid:          str-replace(url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 8 8'%3e%3cpath fill='#{$form-feedback-icon-valid-color}' d='M2.3 6.73L.6 4.53c-.4-1.04.46-1.4 1.1-.8l1.1 1.4 3.4-3.8c.6-.63 1.6-.27 1.2.7l-4 4.6c-.43.5-.8.4-1.1.1z'/%3e%3c/svg%3e"), "#", "%23") !default;
@@ -646,36 +655,6 @@ $form-feedback-icon-invalid-color:  $form-feedback-invalid-color !default;
 $form-feedback-icon-invalid:        str-replace(url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' fill='#{$form-feedback-icon-invalid-color}' viewBox='-2 -2 7 7'%3e%3cpath stroke='%23d9534f' d='M0 0l3 3m0-3L0 3'/%3e%3ccircle r='.5'/%3e%3ccircle cx='3' r='.5'/%3e%3ccircle cy='3' r='.5'/%3e%3ccircle cx='3' cy='3' r='.5'/%3e%3c/svg%3E"), "#", "%23") !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-inner-border-radius:      calc(#{$dropdown-border-radius} - #{$dropdown-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
@@ -709,19 +688,19 @@ $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:              ($spacer / 2) !default;
+$nav-divider-margin-y:              $spacer / 2 !default;
 
 
 // Navbar
 
-$navbar-padding-y:                  ($spacer / 2) !default;
+$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 + $nav-link-padding-y * 2) !default;
+$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;
 
@@ -750,6 +729,37 @@ $navbar-dark-brand-color:                 $navbar-dark-active-color !default;
 $navbar-dark-brand-hover-color:           $navbar-dark-active-color !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-inner-border-radius:      calc(#{$dropdown-border-radius} - #{$dropdown-border-width}) !default;
+$dropdown-divider-bg:               $gray-200 !default;
+$dropdown-divider-margin-y:         $nav-divider-margin-y !default;
+$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;
+
+
 // Pagination
 
 $pagination-padding-y:              .5rem !default;
@@ -801,7 +811,7 @@ $card-bg:                           $white !default;
 
 $card-img-overlay-padding:          1.25rem !default;
 
-$card-group-margin:                 ($grid-gutter-width / 2) !default;
+$card-group-margin:                 $grid-gutter-width / 2 !default;
 $card-deck-margin:                  $card-group-margin !default;
 
 $card-columns-count:                3 !default;
@@ -884,6 +894,9 @@ $badge-padding-y:                   .25em !default;
 $badge-padding-x:                   .4em !default;
 $badge-border-radius:               $border-radius !default;
 
+$badge-transition:                  $btn-transition !default;
+$badge-focus-width:                 $input-btn-focus-width !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.
@@ -909,7 +922,7 @@ $modal-content-box-shadow-sm-up:    0 .5rem 1rem rgba($black, .5) !default;
 
 $modal-backdrop-bg:                 $black !default;
 $modal-backdrop-opacity:            .5 !default;
-$modal-header-border-color:         $gray-200 !default;
+$modal-header-border-color:         $border-color !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;
@@ -951,7 +964,7 @@ $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:                   $primary !default;
+$progress-bar-bg:                   theme-color("primary") !default;
 $progress-bar-animation-timing:     1s linear infinite !default;
 $progress-bar-transition:           width .6s ease !default;
 
diff --git a/scss/bootstrap-grid.scss b/scss/bootstrap-grid.scss
index 16f5f0dfb9..9b3e77cb47 100644
--- a/scss/bootstrap-grid.scss
+++ b/scss/bootstrap-grid.scss
@@ -1,14 +1,10 @@
 /*!
- * Bootstrap Grid v4.1.3 (https://getbootstrap.com/)
+ * Bootstrap Grid v4.2.1 (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;
diff --git a/scss/bootstrap-reboot.scss b/scss/bootstrap-reboot.scss
index 75baeb713e..717417810c 100644
--- a/scss/bootstrap-reboot.scss
+++ b/scss/bootstrap-reboot.scss
@@ -1,5 +1,5 @@
 /*!
- * Bootstrap Reboot v4.1.3 (https://getbootstrap.com/)
+ * Bootstrap Reboot v4.2.1 (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)
diff --git a/scss/bootstrap.scss b/scss/bootstrap.scss
index c9795108c6..44b04b2931 100644
--- a/scss/bootstrap.scss
+++ b/scss/bootstrap.scss
@@ -1,5 +1,5 @@
 /*!
- * Bootstrap v4.1.3 (https://getbootstrap.com/)
+ * Bootstrap v4.2.1 (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)
diff --git a/scss/mixins/_badge.scss b/scss/mixins/_badge.scss
index cf99b3537a..64b29cb579 100644
--- a/scss/mixins/_badge.scss
+++ b/scss/mixins/_badge.scss
@@ -7,5 +7,11 @@
       color: color-yiq($bg);
       background-color: darken($bg, 10%);
     }
+
+    &:focus,
+    &.focus {
+      outline: 0;
+      box-shadow: 0 0 0 $badge-focus-width rgba($bg, .5);
+    }
   }
 }
diff --git a/scss/mixins/_grid-framework.scss b/scss/mixins/_grid-framework.scss
index ff7e1496a6..649c28bf77 100644
--- a/scss/mixins/_grid-framework.scss
+++ b/scss/mixins/_grid-framework.scss
@@ -8,8 +8,8 @@
   %grid-column {
     position: relative;
     width: 100%;
-    padding-right: ($gutter / 2);
-    padding-left: ($gutter / 2);
+    padding-right: $gutter / 2;
+    padding-left: $gutter / 2;
   }
 
   @each $breakpoint in map-keys($breakpoints) {
diff --git a/scss/mixins/_grid.scss b/scss/mixins/_grid.scss
index 254f0734c9..924eb0cfc0 100644
--- a/scss/mixins/_grid.scss
+++ b/scss/mixins/_grid.scss
@@ -2,10 +2,10 @@
 //
 // Generate semantic grid columns with these mixins.
 
-@mixin make-container() {
+@mixin make-container($gutter: $grid-gutter-width) {
   width: 100%;
-  padding-right: ($grid-gutter-width / 2);
-  padding-left: ($grid-gutter-width / 2);
+  padding-right: $gutter / 2;
+  padding-left: $gutter / 2;
   margin-right: auto;
   margin-left: auto;
 }
@@ -20,21 +20,21 @@
   }
 }
 
-@mixin make-row() {
+@mixin make-row($gutter: $grid-gutter-width) {
   display: flex;
   flex-wrap: wrap;
-  margin-right: ($grid-gutter-width / -2);
-  margin-left: ($grid-gutter-width / -2);
+  margin-right: -$gutter / 2;
+  margin-left: -$gutter / 2;
 }
 
-@mixin make-col-ready() {
+@mixin make-col-ready($gutter: $grid-gutter-width) {
   position: relative;
   // Prevent columns from becoming too narrow when at smaller grid tiers by
   // always setting `width: 100%;`. This works because we use `flex` values
   // later on to override this initial width.
   width: 100%;
-  padding-right: ($grid-gutter-width / 2);
-  padding-left: ($grid-gutter-width / 2);
+  padding-right: $gutter / 2;
+  padding-left: $gutter / 2;
 }
 
 @mixin make-col($size, $columns: $grid-columns) {
diff --git a/scss/mixins/_text-emphasis.scss b/scss/mixins/_text-emphasis.scss
index 1819fb03df..155d6ca8cf 100644
--- a/scss/mixins/_text-emphasis.scss
+++ b/scss/mixins/_text-emphasis.scss
@@ -6,9 +6,11 @@
   #{$parent} {
     color: $color !important;
   }
-  a#{$parent} {
-    @include hover-focus {
-      color: darken($color, $emphasized-link-hover-darken-percentage) !important;
+  @if $emphasized-link-hover-darken-percentage != 0 {
+    a#{$parent} {
+      @include hover-focus {
+        color: darken($color, $emphasized-link-hover-darken-percentage) !important;
+      }
     }
   }
 }
diff --git a/scss/utilities/_text.scss b/scss/utilities/_text.scss
index 0edb8e58ba..a04fd097d7 100644
--- a/scss/utilities/_text.scss
+++ b/scss/utilities/_text.scss
@@ -62,6 +62,8 @@
 
 .text-decoration-none { text-decoration: none !important; }
 
+.text-break { word-break: break-word !important; }
+
 // Reset
 
 .text-reset { color: inherit !important; }