Basic guideline adjustments

functions.php

@@ -20,7 +20,7 @@ require get_template_directory() . '/inc/widgets.php';
 /**
  * Load functions to secure your WP install. 
  */
-require get_template_directory() . '/inc/security.php';
+// require get_template_directory() . '/inc/security.php';
 
 /**
  * Enqueue scripts and styles.

gulpfile.js

@@ -271,7 +271,6 @@ gulp.task('copy-assets', ['clean-source'], function() {
     return stream;
 });
 
-
 // Run
 // gulp dist
 // Copies the files to the /dist folder for distribution as simple theme
@@ -280,7 +279,7 @@ gulp.task('dist', ['clean-dist'], function() {
     .pipe(gulp.dest('dist/'))
 });
 
-// Deleting any file inside the /src folder
+// Deleting any file inside the /dist folder
 gulp.task('clean-dist', function () {
   return del(['dist/**/*',]);
 });
@@ -293,7 +292,7 @@ gulp.task('dist-product', ['clean-dist-product'], function() {
     .pipe(gulp.dest('dist-product/'))
 });
 
-// Deleting any file inside the /src folder
+// Deleting any file inside the /dist-product folder
 gulp.task('clean-dist-product', function () {
   return del(['dist-product/**/*',]);
 });

header.php

@@ -70,7 +70,7 @@ $container = get_theme_mod( 'understrap_container_type' );
 						'menu_class'      => 'navbar-nav',
 						'fallback_cb'     => '',
 						'menu_id'         => 'main-menu',
-						'walker'          => new WP_Bootstrap_Navwalker(),
+						'walker'          => new understrap_WP_Bootstrap_Navwalker(),
 					)
 				); ?>
 			<?php if ( 'container' == $container ) : ?>

inc/bootstrap-wp-navwalker.php

@@ -11,7 +11,7 @@ if ( ! defined( 'ABSPATH' ) ) {
 	exit;
 }
 
-if (! class_exists ( 'WP_Bootstrap_Navwalker' )) :
+if (! class_exists ( 'understrap_WP_Bootstrap_Navwalker' )) :
 
 /**
  * Class WP_Bootstrap_Navwalker
@@ -23,7 +23,7 @@ if (! class_exists ( 'WP_Bootstrap_Navwalker' )) :
  * License: GPL-2.0+
  * License URI: http://www.gnu.org/licenses/gpl-2.0.txt
  */
-class WP_Bootstrap_Navwalker extends Walker_Nav_Menu {
+class understrap_WP_Bootstrap_Navwalker extends Walker_Nav_Menu {
 	/**
 	 * The starting level of the menu.
 	 *

inc/custom-comments.php

@@ -6,7 +6,7 @@
  */
 
 // Comments form.
-add_filter( 'comment_form_default_fields', 'bootstrap3_comment_form_fields' );
+add_filter( 'comment_form_default_fields', 'understrap_bootstrap_comment_form_fields' );
 
 /**
  * Creates the comments form.
@@ -15,7 +15,7 @@ add_filter( 'comment_form_default_fields', 'bootstrap3_comment_form_fields' );
  *
  * @return array
  */
-function bootstrap3_comment_form_fields( $fields ) {
+function understrap_bootstrap_comment_form_fields( $fields ) {
 	$commenter = wp_get_current_commenter();
 	$req       = get_option( 'require_name_email' );
 	$aria_req  = ( $req ? " aria-required='true'" : '' );
@@ -35,7 +35,7 @@ function bootstrap3_comment_form_fields( $fields ) {
 	return $fields;
 }
 
-add_filter( 'comment_form_defaults', 'bootstrap3_comment_form' );
+add_filter( 'comment_form_defaults', 'understrap_bootstrap_comment_form' );
 
 /**
  * Builds the form.
@@ -44,7 +44,7 @@ add_filter( 'comment_form_defaults', 'bootstrap3_comment_form' );
  *
  * @return mixed
  */
-function bootstrap3_comment_form( $args ) {
+function understrap_bootstrap_comment_form( $args ) {
 	$args['comment_field'] = '<div class="form-group comment-form-comment">
     <label for="comment">' . _x( 'Comment', 'noun', 'understrap' ) . ( ' <span class="required">*</span>' ) . '</label>
     <textarea class="form-control" id="comment" name="comment" aria-required="true" cols="45" rows="8"></textarea>

inc/enqueue.php

@@ -13,8 +13,8 @@ if ( ! function_exists( 'understrap_scripts' ) ) {
 		// Get the theme data.
 		$the_theme = wp_get_theme();
 		wp_enqueue_style( 'understrap-styles', get_stylesheet_directory_uri() . '/css/theme.min.css', array(), $the_theme->get( 'Version' ), false );
-		wp_register_script('jquery-slim', (get_template_directory_uri() . '/js/jquery.slim.min.js'), true, '3.2.1');
-		wp_enqueue_script( 'jquery-slim' );
+		//wp_register_script('jquery-slim', (get_template_directory_uri() . '/js/jquery.slim.min.js'), true, '3.2.1');
+		//wp_enqueue_script( 'jquery-slim' );
 		wp_enqueue_script( 'popper-scripts', get_template_directory_uri() . '/js/popper.min.js', array(), true);
 		wp_enqueue_script( 'understrap-scripts', get_template_directory_uri() . '/js/theme.min.js', array(), $the_theme->get( 'Version' ), true );
 		if ( is_singular() && comments_open() && get_option( 'thread_comments' ) ) {

sass/theme/_theme_variables.scss

@@ -3,4 +3,4 @@
 // Just copy a variable from src/sass/bootstrap4/_variables.scss, paste it here and edit the value.
 
 
-$primary: #0A42E8; // Thats a sample how you could change a BootStrap variable.
+$primary: #563d7c; // Thats a sample how you could change a BootStrap variable.

src/sass/bootstrap4/_alert.scss

@@ -27,6 +27,8 @@
 // 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;

src/sass/bootstrap4/_button-group.scss

@@ -14,12 +14,12 @@
     // Bring the hover, focused, and "active" buttons to the front to overlay
     // the borders properly
     @include hover {
-      z-index: 2;
+      z-index: 1;
     }
     &:focus,
     &:active,
     &.active {
-      z-index: 2;
+      z-index: 1;
     }
   }
 
@@ -28,7 +28,7 @@
   .btn + .btn-group,
   .btn-group + .btn,
   .btn-group + .btn-group {
-    margin-left: -$input-btn-border-width;
+    margin-left: -$btn-border-width;
   }
 }
 
@@ -43,47 +43,50 @@
   }
 }
 
-.btn-group > .btn:not(:first-child):not(:last-child):not(.dropdown-toggle) {
+.btn-group {
+  > .btn:not(:first-child):not(:last-child):not(.dropdown-toggle) {
     border-radius: 0;
   }
 
   // Set corners individual because sometimes a single button can be in a .btn-group
   // and we need :first-child and :last-child to both match
-.btn-group > .btn:first-child {
+  > .btn:first-child {
     margin-left: 0;
 
     &:not(:last-child):not(.dropdown-toggle) {
       @include border-right-radius(0);
     }
   }
+
+
   // Need .dropdown-toggle since :last-child doesn't apply given a .dropdown-menu
   // immediately after it
-.btn-group > .btn:last-child:not(:first-child),
-.btn-group > .dropdown-toggle:not(:first-child) {
+  > .btn:last-child:not(:first-child),
+  > .dropdown-toggle:not(:first-child) {
     @include border-left-radius(0);
   }
 
   // Custom edits for including btn-groups within btn-groups (useful for including
   // dropdown buttons within a btn-group)
-.btn-group > .btn-group {
+  > .btn-group {
     float: left;
   }
 
-.btn-group > .btn-group:not(:first-child):not(:last-child) > .btn {
+  > .btn-group:not(:first-child):not(:last-child) > .btn {
     border-radius: 0;
   }
 
-.btn-group > .btn-group:first-child:not(:last-child) {
+  > .btn-group:first-child:not(:last-child) {
     > .btn:last-child,
     > .dropdown-toggle {
       @include border-right-radius(0);
     }
   }
 
-.btn-group > .btn-group:last-child:not(:first-child) > .btn:first-child {
+  > .btn-group:last-child:not(:first-child) > .btn:first-child {
     @include border-left-radius(0);
   }
-
+}
 
 // Sizing
 //
@@ -97,9 +100,9 @@
 // Split button dropdowns
 //
 
-.btn + .dropdown-toggle-split {
-  padding-right: $input-btn-padding-x * .75;
-  padding-left: $input-btn-padding-x * .75;
+.dropdown-toggle-split {
+  padding-right: $btn-padding-x * .75;
+  padding-left: $btn-padding-x * .75;
 
   &::after {
     margin-left: 0;
@@ -107,13 +110,13 @@
 }
 
 .btn-sm + .dropdown-toggle-split {
-  padding-right: $input-btn-padding-x-sm * .75;
-  padding-left: $input-btn-padding-x-sm * .75;
+  padding-right: $btn-padding-x-sm * .75;
+  padding-left: $btn-padding-x-sm * .75;
 }
 
 .btn-lg + .dropdown-toggle-split {
-  padding-right: $input-btn-padding-x-lg * .75;
-  padding-left: $input-btn-padding-x-lg * .75;
+  padding-right: $btn-padding-x-lg * .75;
+  padding-left: $btn-padding-x-lg * .75;
 }
 
 
@@ -147,7 +150,7 @@
   > .btn + .btn-group,
   > .btn-group + .btn,
   > .btn-group + .btn-group {
-    margin-top: -$input-btn-border-width;
+    margin-top: -$btn-border-width;
     margin-left: 0;
   }
 
@@ -194,9 +197,11 @@
 // See https://github.com/twbs/bootstrap/pull/12794 and
 // https://github.com/twbs/bootstrap/pull/14559 for more information.
 
-[data-toggle="buttons"] {
+.btn-group-toggle {
   > .btn,
   > .btn-group > .btn {
+    margin-bottom: 0; // Override default `<label>` value
+
     input[type="radio"],
     input[type="checkbox"] {
       position: absolute;

src/sass/bootstrap4/_buttons.scss

@@ -11,8 +11,8 @@
   white-space: nowrap;
   vertical-align: middle;
   user-select: none;
-  border: $input-btn-border-width solid transparent;
-  @include button-size($input-btn-padding-y, $input-btn-padding-x, $font-size-base, $input-btn-line-height, $btn-border-radius);
+  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
@@ -22,20 +22,20 @@
   &:focus,
   &.focus {
     outline: 0;
-    box-shadow: $input-btn-focus-box-shadow;
+    box-shadow: $btn-focus-box-shadow;
   }
 
   // Disabled comes first so active can properly restyle
   &.disabled,
   &:disabled {
-    opacity: .65;
+    opacity: $btn-disabled-opacity;
     @include box-shadow(none);
   }
 
   &:not([disabled]):not(.disabled):active,
   &:not([disabled]):not(.disabled).active {
     background-image: none;
-    @include box-shadow($input-btn-focus-box-shadow, $btn-active-box-shadow);
+    @include box-shadow($btn-focus-box-shadow, $btn-active-box-shadow);
   }
 }
 
@@ -86,6 +86,7 @@ fieldset[disabled] a.btn {
 
   &:focus,
   &.focus {
+    text-decoration: $link-hover-decoration;
     border-color: transparent;
     box-shadow: none;
   }
@@ -104,11 +105,11 @@ fieldset[disabled] a.btn {
 //
 
 .btn-lg {
-  @include button-size($input-btn-padding-y-lg, $input-btn-padding-x-lg, $font-size-lg, $input-btn-line-height-lg, $btn-border-radius-lg);
+  @include button-size($btn-padding-y-lg, $btn-padding-x-lg, $font-size-lg, $btn-line-height-lg, $btn-border-radius-lg);
 }
 
 .btn-sm {
-  @include button-size($input-btn-padding-y-sm, $input-btn-padding-x-sm, $font-size-sm, $input-btn-line-height-sm, $btn-border-radius-sm);
+  @include button-size($btn-padding-y-sm, $btn-padding-x-sm, $font-size-sm, $btn-line-height-sm, $btn-border-radius-sm);
 }
 
 
@@ -119,12 +120,12 @@ fieldset[disabled] a.btn {
 .btn-block {
   display: block;
   width: 100%;
-}
 
   // Vertically space out multiple block buttons
-.btn-block + .btn-block {
+  + .btn-block {
     margin-top: $btn-block-spacing-y;
   }
+}
 
 // Specificity overrides
 input[type="submit"],

src/sass/bootstrap4/_card.scss

@@ -172,14 +172,17 @@
   display: flex;
   flex-direction: column;
 
-  .card {
+  // 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;
-
-    .card {
+    // The child selector allows nested `.card` within `.card-group`
+    // to display properly.
+    > .card {
       // Flexbugs #4: https://github.com/philipwalton/flexbugs#4-flex-shorthand-declarations-with-unitless-flex-basis-values-are-ignored
       flex: 1 0 0%;
       margin-bottom: 0;
@@ -194,10 +197,12 @@
         &:first-child {
           @include border-right-radius(0);
 
-          .card-img-top {
+          .card-img-top,
+          .card-header {
             border-top-right-radius: 0;
           }
-          .card-img-bottom {
+          .card-img-bottom,
+          .card-footer {
             border-bottom-right-radius: 0;
           }
         }
@@ -205,10 +210,12 @@
         &:last-child {
           @include border-left-radius(0);
 
-          .card-img-top {
+          .card-img-top,
+          .card-header {
             border-top-left-radius: 0;
           }
-          .card-img-bottom {
+          .card-img-bottom,
+          .card-footer {
             border-bottom-left-radius: 0;
           }
         }
@@ -216,20 +223,24 @@
         &:only-child {
           @include border-radius($card-border-radius);
 
-          .card-img-top {
+          .card-img-top,
+          .card-header {
             @include border-top-radius($card-border-radius);
           }
-          .card-img-bottom {
+          .card-img-bottom,
+          .card-footer {
             @include border-bottom-radius($card-border-radius);
           }
         }
 
         &:not(:first-child):not(:last-child):not(:only-child) {
-          border-radius: 0;
+          @include border-radius(0);
 
           .card-img-top,
-          .card-img-bottom {
-            border-radius: 0;
+          .card-img-bottom,
+          .card-header,
+          .card-footer {
+            @include border-radius(0);
           }
         }
       }

src/sass/bootstrap4/_close.scss

@@ -22,7 +22,7 @@
 // stylelint-disable property-no-vendor-prefix, selector-no-qualifying-type
 button.close {
   padding: 0;
-  background: transparent;
+  background-color: transparent;
   border: 0;
   -webkit-appearance: none;
 }

src/sass/bootstrap4/_code.scss

@@ -42,8 +42,6 @@ kbd {
 // Blocks of code
 pre {
   display: block;
-  margin-top: 0;
-  margin-bottom: 1rem;
   font-size: $code-font-size;
   color: $pre-color;
 
@@ -53,7 +51,7 @@ pre {
     font-size: inherit;
     color: inherit;
     background-color: transparent;
-    border-radius: 0;
+    @include border-radius(0);
   }
 }
 

src/sass/bootstrap4/_custom-forms.scss

@@ -33,7 +33,7 @@
 
   &:active ~ .custom-control-indicator {
     color: $custom-control-indicator-active-color;
-    @include gradient-bg($custom-control-indicator-active-bg);
+    background-color: $custom-control-indicator-active-bg;
     @include box-shadow($custom-control-indicator-active-box-shadow);
   }
 
@@ -62,10 +62,17 @@
   pointer-events: none;
   user-select: none;
   background-color: $custom-control-indicator-bg;
+  @include box-shadow($custom-control-indicator-box-shadow);
+
+  &::before {
+    display: block;
+    width: $custom-control-indicator-size;
+    height: $custom-control-indicator-size;
+    content: "";
     background-repeat: no-repeat;
     background-position: center center;
     background-size: $custom-control-indicator-bg-size;
-  @include box-shadow($custom-control-indicator-box-shadow);
+  }
 }
 
 // Checkboxes
@@ -78,13 +85,20 @@
   }
 
   .custom-control-input:checked ~ .custom-control-indicator {
+    @include gradient-bg($custom-control-indicator-checked-bg);
+
+    &::before {
       background-image: $custom-checkbox-indicator-icon-checked;
     }
+  }
 
   .custom-control-input:indeterminate ~ .custom-control-indicator {
-    background-color: $custom-checkbox-indicator-indeterminate-bg;
-    background-image: $custom-checkbox-indicator-icon-indeterminate;
+    @include gradient-bg($custom-control-indicator-checked-bg);
     @include box-shadow($custom-checkbox-indicator-indeterminate-box-shadow);
+
+    &::before {
+      background-image: $custom-checkbox-indicator-icon-indeterminate;
+    }
   }
 }
 
@@ -98,9 +112,13 @@
   }
 
   .custom-control-input:checked ~ .custom-control-indicator {
+    @include gradient-bg($custom-control-indicator-checked-bg);
+
+    &::before {
       background-image: $custom-radio-indicator-icon-checked;
     }
   }
+}
 
 
 // Layout options
@@ -148,12 +166,12 @@
 
   &:focus {
     border-color: $custom-select-focus-border-color;
-    outline: none;
-    @include box-shadow($custom-select-focus-box-shadow);
+    outline: 0;
+    box-shadow: $custom-select-focus-box-shadow;
 
     &::-ms-value {
       // For visual consistency with other platforms/browsers,
-      // supress the default white text on blue background highlight given to
+      // 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.
@@ -162,8 +180,10 @@
     }
   }
 
-  &[multiple] {
+  &[multiple],
+  &[size]:not([size="1"]) {
     height: auto;
+    padding-right: $custom-select-padding-x;
     background-image: none;
   }
 
@@ -185,6 +205,13 @@
   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
 //
@@ -206,7 +233,12 @@
   opacity: 0;
 
   &:focus ~ .custom-file-control {
+    border-color: $custom-file-focus-border-color;
     box-shadow: $custom-file-focus-box-shadow;
+
+    &::before {
+      border-color: $custom-file-focus-border-color;
+    }
   }
 }
 
@@ -215,7 +247,6 @@
   top: 0;
   right: 0;
   left: 0;
-  z-index: 5;
   height: $custom-file-height;
   padding: $custom-file-padding-y $custom-file-padding-x;
   line-height: $custom-file-line-height;
@@ -238,7 +269,7 @@
     top: -$custom-file-border-width;
     right: -$custom-file-border-width;
     bottom: -$custom-file-border-width;
-    z-index: 6;
+    z-index: 1;
     display: block;
     height: $custom-file-height;
     padding: $custom-file-padding-y $custom-file-padding-x;

src/sass/bootstrap4/_dropdown.scss

@@ -27,7 +27,7 @@
   background-color: $dropdown-bg;
   background-clip: padding-box;
   border: $dropdown-border-width solid $dropdown-border-color;
-  @include border-radius($border-radius);
+  @include border-radius($dropdown-border-radius);
   @include box-shadow($dropdown-box-shadow);
 }
 
@@ -44,6 +44,34 @@
   }
 }
 
+.dropright {
+  .dropdown-menu {
+    margin-top: 0;
+    margin-left: $dropdown-spacer;
+  }
+
+  .dropdown-toggle {
+    @include caret(right);
+    &::after {
+      vertical-align: 0;
+    }
+  }
+}
+
+.dropleft {
+  .dropdown-menu {
+    margin-top: 0;
+    margin-right: $dropdown-spacer;
+  }
+
+  .dropdown-toggle {
+    @include caret(left);
+    &::before {
+      vertical-align: 0;
+    }
+  }
+}
+
 // Dividers (basically an `<hr>`) within the dropdown
 .dropdown-divider {
   @include nav-divider($dropdown-divider-bg);
@@ -61,7 +89,7 @@
   color: $dropdown-link-color;
   text-align: inherit; // For `<button>`s
   white-space: nowrap; // prevent links from randomly breaking onto new lines
-  background: none; // For `<button>`s
+  background-color: transparent; // For `<button>`s
   border: 0; // For `<button>`s
 
   @include hover-focus {

src/sass/bootstrap4/_forms.scss

@@ -7,15 +7,13 @@
 .form-control {
   display: block;
   width: 100%;
-  padding: $input-btn-padding-y $input-btn-padding-x;
+  padding: $input-padding-y $input-padding-x;
   font-size: $font-size-base;
-  line-height: $input-btn-line-height;
+  line-height: $input-line-height;
   color: $input-color;
   background-color: $input-bg;
-  // Reset unusual Firefox-on-Android default style; see https://github.com/necolas/normalize.css/issues/214.
-  background-image: none;
   background-clip: padding-box;
-  border: $input-btn-border-width solid $input-border-color;
+  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 $enable-rounded {
@@ -88,24 +86,24 @@ select.form-control {
 // For use with horizontal and inline forms, when you need the label text to
 // align with the form controls.
 .col-form-label {
-  padding-top: calc(#{$input-btn-padding-y} + #{$input-btn-border-width});
-  padding-bottom: calc(#{$input-btn-padding-y} + #{$input-btn-border-width});
+  padding-top: calc(#{$input-padding-y} + #{$input-border-width});
+  padding-bottom: calc(#{$input-padding-y} + #{$input-border-width});
   margin-bottom: 0; // Override the `<label>` default
-  line-height: $input-btn-line-height;
+  line-height: $input-line-height;
 }
 
 .col-form-label-lg {
-  padding-top: calc(#{$input-btn-padding-y-lg} + #{$input-btn-border-width});
-  padding-bottom: calc(#{$input-btn-padding-y-lg} + #{$input-btn-border-width});
+  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-btn-line-height-lg;
+  line-height: $input-line-height-lg;
 }
 
 .col-form-label-sm {
-  padding-top: calc(#{$input-btn-padding-y-sm} + #{$input-btn-border-width});
-  padding-bottom: calc(#{$input-btn-padding-y-sm} + #{$input-btn-border-width});
+  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-btn-line-height-sm;
+  line-height: $input-line-height-sm;
 }
 
 
@@ -116,8 +114,8 @@ select.form-control {
 // For use with horizontal and inline forms, when you need the legend text to
 // be the same size as regular labels, and to align with the form controls.
 .col-form-legend {
-  padding-top: $input-btn-padding-y;
-  padding-bottom: $input-btn-padding-y;
+  padding-top: $input-padding-y;
+  padding-bottom: $input-padding-y;
   margin-bottom: 0;
   font-size: $font-size-base;
 }
@@ -129,13 +127,15 @@ select.form-control {
 // text (without any border, background color, focus indicator)
 
 .form-control-plaintext {
-  padding-top: $input-btn-padding-y;
-  padding-bottom: $input-btn-padding-y;
+  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-btn-line-height;
+  line-height: $input-line-height;
   background-color: transparent;
   border: solid transparent;
-  border-width: $input-btn-border-width 0;
+  border-width: $input-border-width 0;
 
   &.form-control-sm,
   &.form-control-lg {
@@ -154,9 +154,9 @@ select.form-control {
 // issue documented in https://github.com/twbs/bootstrap/issues/15074.
 
 .form-control-sm {
-  padding: $input-btn-padding-y-sm $input-btn-padding-x-sm;
+  padding: $input-padding-y-sm $input-padding-x-sm;
   font-size: $font-size-sm;
-  line-height: $input-btn-line-height-sm;
+  line-height: $input-line-height-sm;
   @include border-radius($input-border-radius-sm);
 }
 
@@ -167,9 +167,9 @@ select.form-control-sm {
 }
 
 .form-control-lg {
-  padding: $input-btn-padding-y-lg $input-btn-padding-x-lg;
+  padding: $input-padding-y-lg $input-padding-x-lg;
   font-size: $font-size-lg;
-  line-height: $input-btn-line-height-lg;
+  line-height: $input-line-height-lg;
   @include border-radius($input-border-radius-lg);
 }
 

src/sass/bootstrap4/_functions.scss

@@ -57,13 +57,13 @@
   $yiq: (($r * 299) + ($g * 587) + ($b * 114)) / 1000;
 
   @if ($yiq >= 150) {
-    @return #111;
+    @return $yiq-text-dark;
   } @else {
-    @return #fff;
+    @return $yiq-text-light;
   }
 }
 
-// Retreive color Sass maps
+// Retrieve color Sass maps
 @function color($key: "blue") {
   @return map-get($colors, $key);
 }

src/sass/bootstrap4/_images.scss

@@ -16,7 +16,6 @@
   background-color: $thumbnail-bg;
   border: $thumbnail-border-width solid $thumbnail-border-color;
   @include border-radius($thumbnail-border-radius);
-  @include transition($thumbnail-transition);
   @include box-shadow($thumbnail-box-shadow);
 
   // Keep them at most 100% wide

src/sass/bootstrap4/_input-group.scss

@@ -14,7 +14,7 @@
     // Ensure that the input is always above the *appended* addon button for
     // proper border colors.
     position: relative;
-    z-index: 2;
+    z-index: 1;
     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.
@@ -23,27 +23,39 @@
 
     // Bring the "active" form control to the front
     @include hover-focus-active {
-      z-index: 3;
+      z-index: 2;
     }
   }
 }
 
 .input-group-addon,
 .input-group-btn,
-.input-group .form-control {
+.input-group .form-control,
+.input-group .custom-select,
+.input-group .custom-file {
   display: flex;
   align-items: center;
+
   &:not(:first-child):not(:last-child) {
     @include border-radius(0);
   }
 }
 
+.input-group .custom-file {
+  display: flex;
+  align-items: center;
+}
+
+.input-group .custom-select,
+.input-group .custom-file {
+  width: 100%;
+}
+
 .input-group-addon,
 .input-group-btn {
   white-space: nowrap;
 }
 
-
 // Sizing options
 //
 // Remix the default form control sizing classes into new ones for easier
@@ -66,26 +78,26 @@
 //
 
 .input-group-addon {
-  padding: $input-btn-padding-y $input-btn-padding-x;
+  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-btn-line-height;
+  line-height: $input-line-height;
   color: $input-group-addon-color;
   text-align: center;
   background-color: $input-group-addon-bg;
-  border: $input-btn-border-width solid $input-group-addon-border-color;
+  border: $input-border-width solid $input-group-addon-border-color;
   @include border-radius($input-border-radius);
 
   // Sizing
   &.form-control-sm {
-    padding: $input-btn-padding-y-sm $input-btn-padding-x-sm;
+    padding: $input-padding-y-sm $input-padding-x-sm;
     font-size: $font-size-sm;
     @include border-radius($input-border-radius-sm);
   }
 
   &.form-control-lg {
-    padding: $input-btn-padding-y-lg $input-btn-padding-x-lg;
+    padding: $input-padding-y-lg $input-padding-x-lg;
     font-size: $font-size-lg;
     @include border-radius($input-border-radius-lg);
   }
@@ -103,6 +115,8 @@
 //
 
 .input-group .form-control:not(:last-child),
+.input-group .custom-select:not(:last-child),
+.input-group .custom-file:not(:last-child) .custom-file-control::before,
 .input-group-addon:not(:last-child),
 .input-group-btn:not(:last-child) > .btn,
 .input-group-btn:not(:last-child) > .btn-group > .btn,
@@ -111,10 +125,14 @@
 .input-group-btn:not(:first-child) > .btn-group:not(:last-child) > .btn {
   @include border-right-radius(0);
 }
+
 .input-group-addon:not(:last-child) {
   border-right: 0;
 }
+
 .input-group .form-control:not(:first-child),
+.input-group .custom-select:not(:first-child),
+.input-group .custom-file:not(:first-child) .custom-file-control,
 .input-group-addon:not(:first-child),
 .input-group-btn:not(:first-child) > .btn,
 .input-group-btn:not(:first-child) > .btn-group > .btn,
@@ -123,9 +141,14 @@
 .input-group-btn:not(:last-child) > .btn-group:not(:first-child) > .btn {
   @include border-left-radius(0);
 }
-.form-control + .input-group-addon:not(:first-child) {
+
+.form-control,
+.custom-select,
+.custom-file {
+  + .input-group-addon:not(:first-child) {
     border-left: 0;
   }
+}
 
 //
 // Button input groups
@@ -145,12 +168,12 @@
     position: relative;
 
     + .btn {
-      margin-left: (-$input-btn-border-width);
+      margin-left: (-$input-border-width);
     }
 
     // Bring the "active" button to the front
     @include hover-focus-active {
-      z-index: 3;
+      z-index: 2;
     }
   }
 
@@ -162,24 +185,24 @@
   &:not(:last-child) {
     > .btn,
     > .btn-group {
-      margin-right: (-$input-btn-border-width);
+      margin-right: (-$input-border-width);
     }
   }
   &:not(:first-child) {
     > .btn,
     > .btn-group {
-      z-index: 2;
-      // remove nagative margin ($input-btn-border-width) to solve overlapping issue with button.
+      z-index: 1;
+      // remove nagative margin ($input-border-width) to solve overlapping issue with button.
       margin-left: 0;
 
       // When input is first, overlap the right side of it with the button(-group)
       &:first-child {
-        margin-left: (-$input-btn-border-width);
+        margin-left: (-$input-border-width);
       }
 
       // Because specificity
       @include hover-focus-active {
-        z-index: 3;
+        z-index: 2;
       }
     }
   }

src/sass/bootstrap4/_list-group.scss

@@ -70,7 +70,7 @@
 
   // Include both here for `<a>`s and `<button>`s
   &.active {
-    z-index: 2; // Place active items above their siblings for proper border styling
+    z-index: 1; // 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;
@@ -87,7 +87,7 @@
   .list-group-item {
     border-right: 0;
     border-left: 0;
-    border-radius: 0;
+    @include border-radius(0);
   }
 
   &:first-child {

src/sass/bootstrap4/_modal.scss

@@ -26,17 +26,11 @@
   // gnarly iOS Safari bug: https://bugs.webkit.org/show_bug.cgi?id=158342
   // See also https://github.com/twbs/bootstrap/issues/17695
 
-  // When fading in the modal, animate it to slide down
-  &.fade .modal-dialog {
-    @include transition($modal-transition);
-    transform: translate(0, -25%);
-  }
-  &.show .modal-dialog { transform: translate(0, 0); }
-}
-.modal-open .modal {
+  .modal-open & {
     overflow-x: hidden;
     overflow-y: auto;
   }
+}
 
 // Shell div to position the modal with bottom padding
 .modal-dialog {
@@ -45,6 +39,21 @@
   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));
 }
 
 // Actual modal
@@ -52,6 +61,7 @@
   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;
@@ -141,11 +151,16 @@
     margin: $modal-dialog-margin-y-sm-up auto;
   }
 
+  .modal-dialog-centered {
+    min-height: calc(100% - (#{$modal-dialog-margin-y-sm-up} * 2));
+  }
+
   .modal-content {
     @include box-shadow($modal-content-box-shadow-sm-up);
   }
 
   .modal-sm { max-width: $modal-sm; }
+
 }
 
 @include media-breakpoint-up(lg) {

src/sass/bootstrap4/_nav.scss

@@ -41,7 +41,7 @@
     @include border-top-radius($nav-tabs-border-radius);
 
     @include hover-focus {
-      border-color: $nav-tabs-link-hover-border-color $nav-tabs-link-hover-border-color $nav-tabs-border-color;
+      border-color: $nav-tabs-link-hover-border-color;
     }
 
     &.disabled {
@@ -55,7 +55,7 @@
   .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 $nav-tabs-link-active-border-color $nav-tabs-link-active-bg;
+    border-color: $nav-tabs-link-active-border-color;
   }
 
   .dropdown-menu {

src/sass/bootstrap4/_navbar.scss

@@ -109,7 +109,7 @@
   padding: $navbar-toggler-padding-y $navbar-toggler-padding-x;
   font-size: $navbar-toggler-font-size;
   line-height: 1;
-  background: transparent; // remove default button style
+  background-color: transparent; // remove default button style
   border: $border-width solid transparent; // remove default button style
   @include border-radius($navbar-toggler-border-radius);
 

src/sass/bootstrap4/_pagination.scss

@@ -4,34 +4,6 @@
   @include border-radius();
 }
 
-.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: 2;
-    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;
-    background-color: $pagination-disabled-bg;
-    border-color: $pagination-disabled-border-color;
-  }
-}
-
 .page-link {
   position: relative;
   display: block;
@@ -50,6 +22,34 @@
   }
 }
 
+.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;
+    background-color: $pagination-disabled-bg;
+    border-color: $pagination-disabled-border-color;
+  }
+}
+
 
 //
 // Sizing

src/sass/bootstrap4/_progress.scss

@@ -14,10 +14,12 @@
 
 .progress-bar {
   display: flex;
-  align-items: center;
+  flex-direction: column;
   justify-content: center;
   color: $progress-bar-color;
+  text-align: center;
   background-color: $progress-bar-bg;
+  @include transition($progress-bar-transition);
 }
 
 .progress-bar-striped {

src/sass/bootstrap4/_reboot.scss

@@ -71,7 +71,7 @@ body {
 //
 // Credit: https://github.com/suitcss/base
 [tabindex="-1"]:focus {
-  outline: none !important;
+  outline: 0 !important;
 }
 
 

src/sass/bootstrap4/_tooltip.scss

@@ -34,7 +34,7 @@
     }
 
     .arrow::before {
-      margin-left: -($tooltip-arrow-width - 2);
+      margin-left: -$tooltip-arrow-width;
       content: "";
       border-width: $tooltip-arrow-width $tooltip-arrow-width 0;
       border-top-color: $tooltip-arrow-color;
@@ -47,7 +47,7 @@
     }
 
     .arrow::before {
-      margin-top: -($tooltip-arrow-width - 2);
+      margin-top: -$tooltip-arrow-width;
       content: "";
       border-width: $tooltip-arrow-width $tooltip-arrow-width $tooltip-arrow-width 0;
       border-right-color: $tooltip-arrow-color;
@@ -60,7 +60,7 @@
     }
 
     .arrow::before {
-      margin-left: -($tooltip-arrow-width - 2);
+      margin-left: -$tooltip-arrow-width;
       content: "";
       border-width: 0 $tooltip-arrow-width $tooltip-arrow-width;
       border-bottom-color: $tooltip-arrow-color;
@@ -74,7 +74,7 @@
 
     .arrow::before {
       right: 0;
-      margin-top: -($tooltip-arrow-width - 2);
+      margin-top: -($tooltip-arrow-width);
       content: "";
       border-width: $tooltip-arrow-width 0 $tooltip-arrow-width $tooltip-arrow-width;
       border-left-color: $tooltip-arrow-color;

src/sass/bootstrap4/_type.scss

@@ -53,8 +53,8 @@ h6, .h6 { font-size: $h6-font-size; }
 //
 
 hr {
-  margin-top: 1rem;
-  margin-bottom: 1rem;
+  margin-top: $hr-margin-y;
+  margin-bottom: $hr-margin-y;
   border: 0;
   border-top: $hr-border-width solid $hr-border-color;
 }

src/sass/bootstrap4/_variables.scss

@@ -87,6 +87,10 @@ $theme-colors: map-merge((
 // Set a specific jump point for requesting color jumps
 $theme-color-interval:      8% !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
 //
@@ -217,7 +221,7 @@ $transition-collapse:         height .35s ease !default;
 
 // stylelint-disable value-keyword-case
 $font-family-sans-serif:      -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol" !default;
-$font-family-monospace:       "SFMono-Regular", Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace !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
 
@@ -276,10 +280,12 @@ $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;
 
-$list-inline-padding:         5px !default;
+$list-inline-padding:         .5rem !default;
 
 $mark-bg:                     #fcf8e3 !default;
 
+$hr-margin-y:                 $spacer !default;
+
 
 // Tables
 //
@@ -306,9 +312,9 @@ $table-dark-border-color:     lighten($gray-900, 7.5%) !default;
 $table-dark-color:            $body-bg !default;
 
 
-// Buttons
+// Buttons + Forms
 //
-// For each of Bootstrap's buttons, define text, background and border color.
+// Shared variables that are reassigned to `$input-` and `$btn-` specific variables.
 
 $input-btn-padding-y:         .375rem !default;
 $input-btn-padding-x:         .75rem !default;
@@ -326,8 +332,32 @@ $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;
@@ -339,17 +369,29 @@ $btn-border-radius:           $border-radius !default;
 $btn-border-radius-lg:        $border-radius-lg !default;
 $btn-border-radius-sm:        $border-radius-sm !default;
 
-$btn-transition:              background-color .15s ease-in-out, border-color .15s ease-in-out, box-shadow .15s ease-in-out !default;
+$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
 
+$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-btn-border-width:                $border-width !default; // For form controls and buttons
+$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;
@@ -359,6 +401,8 @@ $input-border-radius-sm:                $border-radius-sm !default;
 $input-focus-bg:                        $input-bg !default;
 $input-focus-border-color:              lighten(theme-color("primary"), 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;
 
@@ -373,7 +417,7 @@ $input-height-sm:                       calc(#{$input-height-inner-sm} + #{$inpu
 $input-height-inner-lg:                 ($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;
 
-$input-transition:                      border-color ease-in-out .15s, box-shadow ease-in-out .15s !default;
+$input-transition:                      border-color .15s ease-in-out, box-shadow .15s ease-in-out !default;
 
 $form-text-margin-top:                  .25rem !default;
 
@@ -395,7 +439,7 @@ $custom-control-spacer-y:               .25rem !default;
 $custom-control-spacer-x:               1rem !default;
 
 $custom-control-indicator-size:         1rem !default;
-$custom-control-indicator-bg:           #ddd !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;
 
@@ -433,21 +477,25 @@ $custom-select-disabled-color:      $gray-600 !default;
 $custom-select-bg:                  $white !default;
 $custom-select-disabled-bg:         $gray-200 !default;
 $custom-select-bg-size:             8px 10px !default; // In pixels because image dimensions
-$custom-select-indicator-color:     #333 !default;
+$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;
 
-$custom-select-focus-border-color:  lighten(theme-color("primary"), 25%) !default;
-$custom-select-focus-box-shadow:    inset 0 1px 2px rgba($black, .075), 0 0 5px rgba($custom-select-focus-border-color, .5) !default;
+$custom-select-focus-border-color:  $input-focus-border-color !default;
+$custom-select-focus-box-shadow:    inset 0 1px 2px rgba($black, .075), $input-btn-focus-box-shadow !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-file-height:                $input-height !default;
 $custom-file-width:                 14rem !default;
-$custom-file-focus-box-shadow:      0 0 0 .075rem $white, 0 0 0 .2rem theme-color("primary") !default;
+$custom-file-focus-border-color:    $input-focus-border-color !default;
+$custom-file-focus-box-shadow:      $input-btn-focus-box-shadow !default;
 
 $custom-file-padding-y:             $input-btn-padding-y !default;
 $custom-file-padding-x:             $input-btn-padding-x !default;
@@ -471,6 +519,8 @@ $custom-file-text: (
 
 
 // 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;
 
@@ -484,6 +534,7 @@ $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;
@@ -522,13 +573,13 @@ $nav-link-padding-y:                .5rem !default;
 $nav-link-padding-x:                1rem !default;
 $nav-link-disabled-color:           $gray-600 !default;
 
-$nav-tabs-border-color:             #ddd !default;
+$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:  $gray-200 !default;
+$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: #ddd !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;
@@ -577,11 +628,11 @@ $pagination-line-height:            1.25 !default;
 $pagination-color:                  $link-color !default;
 $pagination-bg:                     $white !default;
 $pagination-border-width:           $border-width !default;
-$pagination-border-color:           #ddd !default;
+$pagination-border-color:           $gray-300 !default;
 
 $pagination-hover-color:            $link-hover-color !default;
 $pagination-hover-bg:               $gray-200 !default;
-$pagination-hover-border-color:     #ddd !default;
+$pagination-hover-border-color:     $gray-300 !default;
 
 $pagination-active-color:           $white !default;
 $pagination-active-bg:              theme-color("primary") !default;
@@ -589,7 +640,7 @@ $pagination-active-border-color:    theme-color("primary") !default;
 
 $pagination-disabled-color:         $gray-600 !default;
 $pagination-disabled-bg:            $white !default;
-$pagination-disabled-border-color:  #ddd !default;
+$pagination-disabled-border-color:  $gray-300 !default;
 
 
 // Jumbotron
@@ -625,13 +676,12 @@ $tooltip-max-width:                 200px !default;
 $tooltip-color:               $white !default;
 $tooltip-bg:                  $black !default;
 $tooltip-opacity:             .9 !default;
-$tooltip-padding-y:                 3px !default;
-$tooltip-padding-x:                 8px !default;
+$tooltip-padding-y:           .25rem !default;
+$tooltip-padding-x:           .5rem !default;
 $tooltip-margin:              0 !default;
 
-
-$tooltip-arrow-width:               5px !default;
-$tooltip-arrow-height:              5px !default;
+$tooltip-arrow-width:         .4rem !default;
+$tooltip-arrow-height:        $tooltip-arrow-width !default;
 $tooltip-arrow-color:         $tooltip-bg !default;
 
 
@@ -676,18 +726,18 @@ $badge-pill-border-radius:          10rem !default;
 // Modals
 
 // Padding applied to the modal body
-$modal-inner-padding:               15px !default;
+$modal-inner-padding:         1rem !default;
 
-$modal-dialog-margin:               10px !default;
-$modal-dialog-margin-y-sm-up:       30px !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-box-shadow-xs:       0 3px 9px rgba($black,.5) !default;
-$modal-content-box-shadow-sm-up:    0 5px 15px rgba($black,.5) !default;
+$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;
@@ -695,7 +745,7 @@ $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:              15px !default;
+$modal-header-padding:        1rem !default;
 
 $modal-lg:                          800px !default;
 $modal-md:                          500px !default;
@@ -758,10 +808,9 @@ $list-group-action-active-bg:       $gray-200 !default;
 $thumbnail-padding:                 .25rem !default;
 $thumbnail-bg:                      $body-bg !default;
 $thumbnail-border-width:            $border-width !default;
-$thumbnail-border-color:            #ddd !default;
+$thumbnail-border-color:            $gray-300 !default;
 $thumbnail-border-radius:           $border-radius !default;
 $thumbnail-box-shadow:              0 1px 2px rgba($black, .075) !default;
-$thumbnail-transition:              all .2s ease-in-out !default;
 
 
 // Figures

src/sass/bootstrap4/mixins/_breakpoints.scss

@@ -29,13 +29,15 @@
 }
 
 // Maximum breakpoint width. Null for the largest (last) breakpoint.
-// The maximum value is calculated as the minimum of the next one less 0.1.
+// The maximum value is calculated as the minimum of the next one less 0.01px
+// 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
 //
 //    >> breakpoint-max(sm, (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px))
 //    767px
 @function breakpoint-max($name, $breakpoints: $grid-breakpoints) {
   $next: breakpoint-next($name, $breakpoints);
-  @return if($next, breakpoint-min($next, $breakpoints) - 1px, null);
+  @return if($next, breakpoint-min($next, $breakpoints) - .01px, null);
 }
 
 // Returns a blank string if smallest breakpoint, otherwise returns the name with a dash infront.

src/sass/bootstrap4/mixins/_buttons.scss

@@ -19,9 +19,9 @@
   &.focus {
     // Avoid using mixin so we can pass custom focus shadow properly
     @if $enable-shadows {
-      box-shadow: $btn-box-shadow, 0 0 0 $input-btn-focus-width rgba($border, .5);
+      box-shadow: $btn-box-shadow, 0 0 0 $btn-focus-width rgba($border, .5);
     } @else {
-      box-shadow: 0 0 0 $input-btn-focus-width rgba($border, .5);
+      box-shadow: 0 0 0 $btn-focus-width rgba($border, .5);
     }
   }
 
@@ -44,28 +44,28 @@
 
     // Avoid using mixin so we can pass custom focus shadow properly
     @if $enable-shadows {
-      box-shadow: $btn-active-box-shadow, 0 0 0 $input-btn-focus-width rgba($border, .5);
+      box-shadow: $btn-active-box-shadow, 0 0 0 $btn-focus-width rgba($border, .5);
     } @else {
-      box-shadow: 0 0 0 $input-btn-focus-width rgba($border, .5);
+      box-shadow: 0 0 0 $btn-focus-width rgba($border, .5);
     }
   }
 }
 
-@mixin button-outline-variant($color, $color-hover: #fff) {
+@mixin button-outline-variant($color, $color-hover: #fff, $active-background: $color, $active-border: $color) {
   color: $color;
   background-color: transparent;
   background-image: none;
   border-color: $color;
 
-  @include hover {
-    color: $color-hover;
-    background-color: $color;
-    border-color: $color;
+  &:hover {
+    color: color-yiq($color);
+    background-color: $active-background;
+    border-color: $active-border;
   }
 
   &:focus,
   &.focus {
-    box-shadow: 0 0 0 $input-btn-focus-width rgba($color, .5);
+    box-shadow: 0 0 0 $btn-focus-width rgba($color, .5);
   }
 
   &.disabled,
@@ -77,11 +77,11 @@
   &:not([disabled]):not(.disabled):active,
   &:not([disabled]):not(.disabled).active,
   .show > &.dropdown-toggle {
-    color: $color-hover;
-    background-color: $color;
-    border-color: $color;
+    color: color-yiq($color-hover);
+    background-color: $active-background;
+    border-color: $active-border;
     // Avoid using mixin so we can pass custom focus shadow properly
-    box-shadow: 0 0 0 $input-btn-focus-width rgba($color, .5);
+    box-shadow: 0 0 0 $btn-focus-width rgba($color, .5);
   }
 }
 
@@ -90,5 +90,10 @@
   padding: $padding-y $padding-x;
   font-size: $font-size;
   line-height: $line-height;
-  @include border-radius($border-radius);
+  // Manually declare to provide an override to the browser default
+  @if $enable-rounded {
+    border-radius: $border-radius;
+  } @else {
+    border-radius: 0;
+  }
 }

src/sass/bootstrap4/mixins/_caret.scss

@@ -12,6 +12,18 @@
   border-left: $caret-width solid transparent;
 }
 
+@mixin caret-right {
+  border-top: $caret-width solid transparent;
+  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 {
@@ -25,6 +37,24 @@
         @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;
       }
     }
 

src/sass/bootstrap4/mixins/_forms.scss

@@ -15,12 +15,12 @@
     color: $input-focus-color;
     background-color: $input-focus-bg;
     border-color: $input-focus-border-color;
-    outline: none;
+    outline: 0;
     // Avoid using mixin so we can pass custom focus shadow properly
     @if $enable-shadows {
-      box-shadow: $input-box-shadow, $input-btn-focus-box-shadow;
+      box-shadow: $input-box-shadow, $input-focus-box-shadow;
     } @else {
-      box-shadow: $input-btn-focus-box-shadow;
+      box-shadow: $input-focus-box-shadow;
     }
   }
 }
@@ -30,8 +30,8 @@
 
   .#{$state}-feedback {
     display: none;
-    margin-top: .25rem;
-    font-size: .875rem;
+    margin-top: $form-feedback-margin-top;
+    font-size: $form-feedback-font-size;
     color: $color;
   }
 
@@ -57,7 +57,8 @@
       border-color: $color;
 
       &:focus {
-        box-shadow: 0 0 0 .2rem rgba($color,.25);
+        border-color: $color;
+        box-shadow: 0 0 0 $input-focus-width rgba($color, .25);
       }
 
       ~ .#{$state}-feedback,
@@ -83,11 +84,21 @@
     .was-validated &:#{$state},
     &.is-#{$state} {
       ~ .custom-control-indicator {
-        background-color: rgba($color, .25);
+        background-color: lighten($color, 25%);
       }
       ~ .custom-control-description {
         color: $color;
       }
+      &:checked {
+        ~ .custom-control-indicator {
+          @include gradient-bg(lighten($color, 10%));
+        }
+      }
+      &:focus {
+        ~ .custom-control-indicator {
+          box-shadow: 0 0 0 1px $body-bg, 0 0 0 $input-focus-width rgba($color, .25);
+        }
+      }
     }
   }
 
@@ -101,7 +112,9 @@
         &::before { border-color: inherit; }
       }
       &:focus {
-        box-shadow: 0 0 0 .2rem rgba($color,.25);
+        ~ .custom-file-control {
+          box-shadow: 0 0 0 $input-focus-width rgba($color, .25);
+        }
       }
     }
   }