Train PR: CSS variables for accordion, cards, navs, and modals (#36071)

* Convert accordion to CSS vars

* Update accordion.md

* Convert navs to CSS variables

* Split up CSS vars

* bundlewatch

* fix vars

* Convert cards to CSS vars

* Convert modals to CSS variables

* Bundlewatch

Co-authored-by: Geremia Taglialatela <tagliala.dev@gmail.com>

10 files changed, 256 insertions, 114 deletions

diff --git a/.bundlewatch.config.json b/.bundlewatch.config.json
index 43c10d546c..6fcfbb2a72 100644
--- a/.bundlewatch.config.json
+++ b/.bundlewatch.config.json
@@ -26,11 +26,11 @@
     },
     {
       "path": "./dist/css/bootstrap.css",
-      "maxSize": "26.9 kB"
+      "maxSize": "27.6 kB"
     },
     {
       "path": "./dist/css/bootstrap.min.css",
-      "maxSize": "25 kB"
+      "maxSize": "25.65 kB"
     },
     {
       "path": "./dist/js/bootstrap.bundle.js",
diff --git a/scss/_accordion.scss b/scss/_accordion.scss
index 53f1c0ccfc..aac63ce2ff 100644
--- a/scss/_accordion.scss
+++ b/scss/_accordion.scss
@@ -2,14 +2,30 @@
 // Base styles
 //
 
+.accordion {
+  // scss-docs-start accordion-css-vars
+  --#{$prefix}accordion-color: #{$accordion-color};
+  --#{$prefix}accordion-bg: #{$accordion-bg};
+  --#{$prefix}accordion-border-color: #{$accordion-border-color};
+  --#{$prefix}accordion-border-width: #{$accordion-border-width};
+  --#{$prefix}accordion-border-radius: #{$accordion-border-radius};
+  --#{$prefix}accordion-btn-padding-x: #{$accordion-button-padding-x};
+  --#{$prefix}accordion-btn-padding-y: #{$accordion-button-padding-y};
+  --#{$prefix}accordion-body-padding-x: #{$accordion-body-padding-x};
+  --#{$prefix}accordion-body-padding-y: #{$accordion-body-padding-y};
+  --#{$prefix}accordion-active-color: #{$accordion-button-active-color};
+  --#{$prefix}accordion-active-bg: #{$accordion-button-active-bg};
+  // scss-docs-end accordion-css-vars
+}
+
 .accordion-button {
   position: relative;
   display: flex;
   align-items: center;
   width: 100%;
-  padding: $accordion-button-padding-y $accordion-button-padding-x;
+  padding: var(--#{$prefix}accordion-btn-padding-y) var(--#{$prefix}accordion-btn-padding-x);
   @include font-size($font-size-base);
-  color: $accordion-button-color;
+  color: var(--#{$prefix}accordion-color);
   text-align: left; // Reset button style
   background-color: $accordion-button-bg;
   border: 0;
@@ -18,9 +34,9 @@
   @include transition($accordion-transition);
 
   &:not(.collapsed) {
-    color: $accordion-button-active-color;
-    background-color: $accordion-button-active-bg;
-    box-shadow: inset 0 calc($accordion-border-width * -1) 0 $accordion-border-color; // stylelint-disable-line function-disallowed-list
+    color: var(--#{$prefix}accordion-active-color);
+    background-color: var(--#{$prefix}accordion-active-bg);
+    box-shadow: inset 0 calc(var(--#{$prefix}accordion-border-width) * -1) 0 var(--#{$prefix}accordion-border-color); // stylelint-disable-line function-disallowed-list
 
     &::after {
       background-image: escape-svg($accordion-button-active-icon);
@@ -59,14 +75,14 @@
 
 .accordion-item {
   color: color-contrast($accordion-bg);
-  background-color: $accordion-bg;
-  border: $accordion-border-width solid $accordion-border-color;
+  background-color: var(--#{$prefix}accordion-bg);
+  border: var(--#{$prefix}accordion-border-width) solid var(--#{$prefix}accordion-border-color);
 
   &:first-of-type {
-    @include border-top-radius($accordion-border-radius);
+    @include border-top-radius(var(--#{$prefix}accordion-border-radius));
 
     .accordion-button {
-      @include border-top-radius($accordion-inner-border-radius);
+      @include border-top-radius($accordion-inner-border-radius); // todo
     }
   }
 
@@ -76,22 +92,22 @@
 
   // Only set a border-radius on the last item if the accordion is collapsed
   &:last-of-type {
-    @include border-bottom-radius($accordion-border-radius);
+    @include border-bottom-radius(var(--#{$prefix}accordion-border-radius));
 
     .accordion-button {
       &.collapsed {
-        @include border-bottom-radius($accordion-inner-border-radius);
+        @include border-bottom-radius($accordion-inner-border-radius); // todo
       }
     }
 
     .accordion-collapse {
-      @include border-bottom-radius($accordion-border-radius);
+      @include border-bottom-radius(var(--#{$prefix}accordion-border-radius));
     }
   }
 }
 
 .accordion-body {
-  padding: $accordion-body-padding-y $accordion-body-padding-x;
+  padding: var(--#{$prefix}accordion-body-padding-y) var(--#{$prefix}accordion-body-padding-x);
 }
 
 
diff --git a/scss/_card.scss b/scss/_card.scss
index 22890f5c97..ce8c02f1f2 100644
--- a/scss/_card.scss
+++ b/scss/_card.scss
@@ -3,17 +3,37 @@
 //
 
 .card {
+  // scss-docs-start card-css-vars
+  --#{$prefix}card-spacer-y: #{$card-spacer-y};
+  --#{$prefix}card-spacer-x: #{$card-spacer-x};
+  --#{$prefix}card-title-spacer-y: #{$card-title-spacer-y};
+  --#{$prefix}card-border-width: #{$card-border-width};
+  --#{$prefix}card-border-color: #{$card-border-color};
+  --#{$prefix}card-border-radius: #{$card-border-radius};
+  --#{$prefix}card-box-shadow: #{$card-box-shadow};
+  --#{$prefix}card-inner-border-radius: #{$card-inner-border-radius};
+  --#{$prefix}card-cap-padding-y: #{$card-cap-padding-y};
+  --#{$prefix}card-cap-padding-x: #{$card-cap-padding-x};
+  --#{$prefix}card-cap-bg: #{$card-cap-bg};
+  --#{$prefix}card-cap-color: #{$card-cap-color};
+  --#{$prefix}card-height: #{$card-height};
+  --#{$prefix}card-color: #{$card-color};
+  --#{$prefix}card-bg: #{$card-bg};
+  --#{$prefix}card-img-overlay-padding: #{$card-img-overlay-padding};
+  --#{$prefix}card-group-margin: #{$card-group-margin};
+  // scss-docs-end card-css-vars
+
   position: relative;
   display: flex;
   flex-direction: column;
   min-width: 0; // See https://github.com/twbs/bootstrap/pull/22740#issuecomment-305868106
-  height: $card-height;
+  height: var(--#{$prefix}card-height);
   word-wrap: break-word;
-  background-color: $card-bg;
+  background-color: var(--#{$prefix}card-bg);
   background-clip: border-box;
-  border: $card-border-width solid $card-border-color;
-  @include border-radius($card-border-radius);
-  @include box-shadow($card-box-shadow);
+  border: var(--#{$prefix}card-border-width) solid var(--#{$prefix}card-border-color);
+  @include border-radius(var(--#{$prefix}card-border-radius));
+  @include box-shadow(var(--#{$prefix}card-box-shadow));
 
   > hr {
     margin-right: 0;
@@ -26,12 +46,12 @@
 
     &:first-child {
       border-top-width: 0;
-      @include border-top-radius($card-inner-border-radius);
+      @include border-top-radius(var(--#{$prefix}card-inner-border-radius));
     }
 
     &:last-child  {
       border-bottom-width: 0;
-      @include border-bottom-radius($card-inner-border-radius);
+      @include border-bottom-radius(var(--#{$prefix}card-inner-border-radius));
     }
   }
 
@@ -47,16 +67,16 @@
   // 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-y $card-spacer-x;
-  color: $card-color;
+  padding: var(--#{$prefix}card-spacer-y) var(--#{$prefix}card-spacer-x);
+  color: var(--#{$prefix}card-color);
 }
 
 .card-title {
-  margin-bottom: $card-title-spacer-y;
+  margin-bottom: var(--#{$prefix}card-title-spacer-y);
 }
 
 .card-subtitle {
-  margin-top: -$card-title-spacer-y * .5;
+  margin-top: calc(-.5 * var(--#{$prefix}card-title-spacer-y)); // stylelint-disable-line function-disallowed-list
   margin-bottom: 0;
 }
 
@@ -70,7 +90,7 @@
   }
 
   + .card-link {
-    margin-left: $card-spacer-x;
+    margin-left: var(--#{$prefix}card-spacer-x);
   }
 }
 
@@ -79,25 +99,25 @@
 //
 
 .card-header {
-  padding: $card-cap-padding-y $card-cap-padding-x;
+  padding: var(--#{$prefix}card-cap-padding-y) var(--#{$prefix}card-cap-padding-x);
   margin-bottom: 0; // Removes the default margin-bottom of <hN>
-  color: $card-cap-color;
-  background-color: $card-cap-bg;
-  border-bottom: $card-border-width solid $card-border-color;
+  color: var(--#{$prefix}card-cap-color);
+  background-color: var(--#{$prefix}card-cap-bg);
+  border-bottom: var(--#{$prefix}card-border-width) solid var(--#{$prefix}card-border-color);
 
   &:first-child {
-    @include border-radius($card-inner-border-radius $card-inner-border-radius 0 0);
+    @include border-radius(var(--#{$prefix}card-inner-border-radius) var(--#{$prefix}card-inner-border-radius) 0 0);
   }
 }
 
 .card-footer {
-  padding: $card-cap-padding-y $card-cap-padding-x;
-  color: $card-cap-color;
-  background-color: $card-cap-bg;
-  border-top: $card-border-width solid $card-border-color;
+  padding: var(--#{$prefix}card-cap-padding-y) var(--#{$prefix}card-cap-padding-x);
+  color: var(--#{$prefix}card-cap-color);
+  background-color: var(--#{$prefix}card-cap-bg);
+  border-top: var(--#{$prefix}card-border-width) solid var(--#{$prefix}card-border-color);
 
   &:last-child {
-    @include border-radius(0 0 $card-inner-border-radius $card-inner-border-radius);
+    @include border-radius(0 0 var(--#{$prefix}card-inner-border-radius) var(--#{$prefix}card-inner-border-radius));
   }
 }
 
@@ -107,22 +127,20 @@
 //
 
 .card-header-tabs {
-  margin-right: -$card-cap-padding-x * .5;
-  margin-bottom: -$card-cap-padding-y;
-  margin-left: -$card-cap-padding-x * .5;
+  margin-right: calc(-.5 * var(--#{$prefix}card-cap-padding-x)); // stylelint-disable-line function-disallowed-list
+  margin-bottom: calc(-1 * var(--#{$prefix}card-cap-padding-y)); // stylelint-disable-line function-disallowed-list
+  margin-left: calc(-.5 * var(--#{$prefix}card-cap-padding-x)); // stylelint-disable-line function-disallowed-list
   border-bottom: 0;
 
-  @if $nav-tabs-link-active-bg != $card-bg {
-    .nav-link.active {
-      background-color: $card-bg;
-      border-bottom-color: $card-bg;
-    }
+  .nav-link.active {
+    background-color: var(--#{$prefix}card-bg);
+    border-bottom-color: var(--#{$prefix}card-bg);
   }
 }
 
 .card-header-pills {
-  margin-right: -$card-cap-padding-x * .5;
-  margin-left: -$card-cap-padding-x * .5;
+  margin-right: calc(-.5 * var(--#{$prefix}card-cap-padding-x)); // stylelint-disable-line function-disallowed-list
+  margin-left: calc(-.5 * var(--#{$prefix}card-cap-padding-x)); // stylelint-disable-line function-disallowed-list
 }
 
 // Card image
@@ -132,8 +150,8 @@
   right: 0;
   bottom: 0;
   left: 0;
-  padding: $card-img-overlay-padding;
-  @include border-radius($card-inner-border-radius);
+  padding: var(--#{$prefix}card-img-overlay-padding);
+  @include border-radius(var(--#{$prefix}card-inner-border-radius));
 }
 
 .card-img,
@@ -144,12 +162,12 @@
 
 .card-img,
 .card-img-top {
-  @include border-top-radius($card-inner-border-radius);
+  @include border-top-radius(var(--#{$prefix}card-inner-border-radius));
 }
 
 .card-img,
 .card-img-bottom {
-  @include border-bottom-radius($card-inner-border-radius);
+  @include border-bottom-radius(var(--#{$prefix}card-inner-border-radius));
 }
 
 
@@ -161,7 +179,7 @@
   // The child selector allows nested `.card` within `.card-group`
   // to display properly.
   > .card {
-    margin-bottom: $card-group-margin;
+    margin-bottom: var(--#{$prefix}card-group-margin);
   }
 
   @include media-breakpoint-up(sm) {
diff --git a/scss/_modal.scss b/scss/_modal.scss
index 7fa82191fd..6b341a895e 100644
--- a/scss/_modal.scss
+++ b/scss/_modal.scss
@@ -1,3 +1,5 @@
+// stylelint-disable function-disallowed-list
+
 // .modal-open      - body class for killing the scroll
 // .modal           - container to scroll within
 // .modal-dialog    - positioning shell for the actual modal
@@ -6,10 +8,34 @@
 
 // Container that the modal scrolls within
 .modal {
+  // scss-docs-start modal-css-vars
+  --#{$prefix}modal-zindex: #{$zindex-modal};
+  --#{$prefix}modal-width: #{$modal-md};
+  --#{$prefix}modal-padding: #{$modal-inner-padding};
+  --#{$prefix}modal-margin: #{$modal-dialog-margin};
+  --#{$prefix}modal-color: #{$modal-content-color};
+  --#{$prefix}modal-bg: #{$modal-content-bg};
+  --#{$prefix}modal-border-color: #{$modal-content-border-color};
+  --#{$prefix}modal-border-width: #{$modal-content-border-width};
+  --#{$prefix}modal-border-radius: #{$modal-content-border-radius};
+  --#{$prefix}modal-box-shadow: #{$modal-content-box-shadow-xs};
+  --#{$prefix}modal-inner-border-radius: #{$modal-content-inner-border-radius};
+  --#{$prefix}modal-header-padding-x: #{$modal-header-padding-x};
+  --#{$prefix}modal-header-padding-y: #{$modal-header-padding-y};
+  --#{$prefix}modal-header-padding: #{$modal-header-padding}; // Todo in v6: Split this padding into x and y
+  --#{$prefix}modal-header-border-color: #{$modal-header-border-color};
+  --#{$prefix}modal-header-border-width: #{$modal-header-border-width};
+  --#{$prefix}modal-title-line-height: #{$modal-title-line-height};
+  --#{$prefix}modal-footer-gap: #{$modal-footer-margin-between};
+  --#{$prefix}modal-footer-bg: #{$modal-footer-bg};
+  --#{$prefix}modal-footer-border-color: #{$modal-footer-border-color};
+  --#{$prefix}modal-footer-border-width: #{$modal-footer-border-width};
+  // scss-docs-end modal-css-vars
+
   position: fixed;
   top: 0;
   left: 0;
-  z-index: $zindex-modal;
+  z-index: var(--#{$prefix}modal-zindex);
   display: none;
   width: 100%;
   height: 100%;
@@ -28,7 +54,7 @@
 .modal-dialog {
   position: relative;
   width: auto;
-  margin: $modal-dialog-margin;
+  margin: var(--#{$prefix}modal-margin);
   // allow clicks to pass through for custom click handling to close modal
   pointer-events: none;
 
@@ -48,7 +74,7 @@
 }
 
 .modal-dialog-scrollable {
-  height: subtract(100%, $modal-dialog-margin * 2);
+  height: calc(100% - var(--#{$prefix}modal-margin) * 2);
 
   .modal-content {
     max-height: 100%;
@@ -63,7 +89,7 @@
 .modal-dialog-centered {
   display: flex;
   align-items: center;
-  min-height: subtract(100%, $modal-dialog-margin * 2);
+  min-height: calc(100% - var(--#{$prefix}modal-margin) * 2);
 }
 
 // Actual modal
@@ -73,20 +99,26 @@
   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
-  color: $modal-content-color;
+  color: var(--#{$prefix}modal-color);
   pointer-events: auto;
-  background-color: $modal-content-bg;
+  background-color: var(--#{$prefix}modal-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($modal-content-box-shadow-xs);
+  border: var(--#{$prefix}modal-border-width) solid var(--#{$prefix}modal-border-color);
+  @include border-radius(var(--#{$prefix}modal-border-radius));
+  @include box-shadow(var(--#{$prefix}modal-box-shadow));
   // Remove focus outline from opened modal
   outline: 0;
 }
 
 // Modal background
 .modal-backdrop {
-  @include overlay-backdrop($zindex-modal-backdrop, $modal-backdrop-bg, $modal-backdrop-opacity);
+  // scss-docs-start modal-backdrop-css-vars
+  --#{$prefix}backdrop-zindex: #{$zindex-modal-backdrop};
+  --#{$prefix}backdrop-bg: #{$modal-backdrop-bg};
+  --#{$prefix}backdrop-opacity: #{$modal-backdrop-opacity};
+  // scss-docs-end modal-backdrop-css-vars
+
+  @include overlay-backdrop(var(--#{$prefix}backdrop-zindex), var(--#{$prefix}backdrop-bg), var(--#{$prefix}backdrop-opacity));
 }
 
 // Modal header
@@ -96,20 +128,20 @@
   flex-shrink: 0;
   align-items: center;
   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-inner-border-radius);
+  padding: var(--#{$prefix}modal-header-padding);
+  border-bottom: var(--#{$prefix}modal-header-border-width) solid var(--#{$prefix}modal-header-border-color);
+  @include border-top-radius(var(--#{$prefix}modal-inner-border-radius));
 
   .btn-close {
-    padding: ($modal-header-padding-y * .5) ($modal-header-padding-x * .5);
-    margin: ($modal-header-padding-y * -.5) ($modal-header-padding-x * -.5) ($modal-header-padding-y * -.5) auto;
+    padding: calc(var(--#{$prefix}modal-header-padding-y) * .5) calc(var(--#{$prefix}modal-header-padding-x) * .5);
+    margin: calc(var(--#{$prefix}modal-header-padding-y) * -.5) calc(var(--#{$prefix}modal-header-padding-x) * -.5) calc(var(--#{$prefix}modal-header-padding-y) * -.5) auto;
   }
 }
 
 // Title text within header
 .modal-title {
   margin-bottom: 0;
-  line-height: $modal-title-line-height;
+  line-height: var(--#{$prefix}modal-title-line-height);
 }
 
 // Modal body
@@ -119,7 +151,7 @@
   // Enable `flex-grow: 1` so that the body take up as much space as possible
   // when there should be a fixed height on `.modal-dialog`.
   flex: 1 1 auto;
-  padding: $modal-inner-padding;
+  padding: var(--#{$prefix}modal-padding);
 }
 
 // Footer (for actions)
@@ -129,16 +161,16 @@
   flex-wrap: wrap;
   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 - $modal-footer-margin-between * .5;
-  background-color: $modal-footer-bg;
-  border-top: $modal-footer-border-width solid $modal-footer-border-color;
-  @include border-bottom-radius($modal-content-inner-border-radius);
+  padding: calc(var(--#{$prefix}modal-padding) - var(--#{$prefix}modal-footer-gap) * .5);
+  background-color: var(--#{$prefix}modal-footer-bg);
+  border-top: var(--#{$prefix}modal-footer-border-width) solid var(--#{$prefix}modal-footer-border-color);
+  @include border-bottom-radius(var(--#{$prefix}modal-inner-border-radius));
 
   // Place margin between footer elements
   // This solution is far from ideal because of the universal selector usage,
   // but is needed to fix https://github.com/twbs/bootstrap/issues/24800
   > * {
-    margin: $modal-footer-margin-between * .5;
+    margin: calc(var(--#{$prefix}modal-footer-gap) * .5); // Todo in v6: replace with gap on parent class
   }
 }
 
@@ -146,34 +178,41 @@
 @include media-breakpoint-up(sm) {
   // Automatically set modal's width for larger viewports
   .modal-dialog {
-    max-width: $modal-md;
-    margin: $modal-dialog-margin-y-sm-up auto;
+    --#{$prefix}modal-margin: #{$modal-dialog-margin-y-sm-up};
+
+    max-width: var(--#{$prefix}modal-width);
+    margin-right: auto;
+    margin-left: auto;
   }
 
   .modal-dialog-scrollable {
-    height: subtract(100%, $modal-dialog-margin-y-sm-up * 2);
+    height: calc(100% - var(--#{$prefix}modal-margin) * 2);
   }
 
   .modal-dialog-centered {
-    min-height: subtract(100%, $modal-dialog-margin-y-sm-up * 2);
+    min-height: calc(100% - var(--#{$prefix}modal-margin) * 2);
   }
 
   .modal-content {
-    @include box-shadow($modal-content-box-shadow-sm-up);
+    --#{$prefix}modal-box-shadow: #{$modal-content-box-shadow-sm-up};
   }
 
-  .modal-sm { max-width: $modal-sm; }
+  .modal-sm {
+    --#{$prefix}modal-width: #{$modal-sm};
+  }
 }
 
 @include media-breakpoint-up(lg) {
   .modal-lg,
   .modal-xl {
-    max-width: $modal-lg;
+    --#{$prefix}modal-width: #{$modal-lg};
   }
 }
 
 @include media-breakpoint-up(xl) {
-  .modal-xl { max-width: $modal-xl; }
+  .modal-xl {
+    --#{$prefix}modal-width: #{$modal-xl};
+  }
 }
 
 // scss-docs-start modal-fullscreen-loop
@@ -194,17 +233,14 @@
         @include border-radius(0);
       }
 
-      .modal-header {
+      .modal-header,
+      .modal-footer {
         @include border-radius(0);
       }
 
       .modal-body {
         overflow-y: auto;
       }
-
-      .modal-footer {
-        @include border-radius(0);
-      }
     }
   }
 }
diff --git a/scss/_nav.scss b/scss/_nav.scss
index 62a2fa6828..21ee1b2b44 100644
--- a/scss/_nav.scss
+++ b/scss/_nav.scss
@@ -4,6 +4,16 @@
 // `<nav>`s, `<ul>`s or `<ol>`s.
 
 .nav {
+  // scss-docs-start nav-css-vars
+  --#{$prefix}nav-link-padding-x: #{$nav-link-padding-x};
+  --#{$prefix}nav-link-padding-y: #{$nav-link-padding-y};
+  @include rfs($nav-link-font-size, --#{$prefix}nav-link-font-size);
+  --#{$prefix}nav-link-font-weight: #{$nav-link-font-weight}; // stylelint-disable-line custom-property-empty-line-before
+  --#{$prefix}nav-link-color: #{$nav-link-color};
+  --#{$prefix}nav-link-hover-color: #{$nav-link-hover-color};
+  --#{$prefix}nav-link-disabled-color: #{$nav-link-disabled-color};
+  // scss-docs-end nav-css-vars
+
   display: flex;
   flex-wrap: wrap;
   padding-left: 0;
@@ -13,22 +23,22 @@
 
 .nav-link {
   display: block;
-  padding: $nav-link-padding-y $nav-link-padding-x;
-  @include font-size($nav-link-font-size);
-  font-weight: $nav-link-font-weight;
-  color: $nav-link-color;
+  padding: var(--#{$prefix}nav-link-padding-y) var(--#{$prefix}nav-link-padding-x);
+  @include font-size(var(--#{$prefix}nav-link-font-size));
+  font-weight: var(--#{$prefix}nav-link-font-weight);
+  color: var(--#{$prefix}nav-link-color);
   text-decoration: if($link-decoration == none, null, none);
   @include transition($nav-link-transition);
 
   &:hover,
   &:focus {
-    color: $nav-link-hover-color;
+    color: var(--#{$prefix}nav-link-hover-color);
     text-decoration: if($link-hover-decoration == underline, none, null);
   }
 
   // Disabled state lightens text
   &.disabled {
-    color: $nav-link-disabled-color;
+    color: var(--#{$prefix}nav-link-disabled-color);
     pointer-events: none;
     cursor: default;
   }
@@ -39,23 +49,33 @@
 //
 
 .nav-tabs {
-  border-bottom: $nav-tabs-border-width solid $nav-tabs-border-color;
+  // scss-docs-start nav-tabs-css-vars
+  --#{$prefix}nav-tabs-border-width: #{$nav-tabs-border-width};
+  --#{$prefix}nav-tabs-border-color: #{$nav-tabs-border-color};
+  --#{$prefix}nav-tabs-border-radius: #{$nav-tabs-border-radius};
+  --#{$prefix}nav-tabs-link-hover-border-color: #{$nav-tabs-link-hover-border-color};
+  --#{$prefix}nav-tabs-link-active-color: #{$nav-tabs-link-active-color};
+  --#{$prefix}nav-tabs-link-active-bg: #{$nav-tabs-link-active-bg};
+  --#{$prefix}nav-tabs-link-active-border-color: #{$nav-tabs-link-active-border-color};
+  // scss-docs-end nav-tabs-css-vars
+
+  border-bottom: var(--#{$prefix}nav-tabs-border-width) solid var(--#{$prefix}nav-tabs-border-color);
 
   .nav-link {
-    margin-bottom: calc($nav-tabs-border-width * -1); // stylelint-disable-line function-disallowed-list
+    margin-bottom: calc(var(--#{$prefix}nav-tabs-border-width) * -1); // stylelint-disable-line function-disallowed-list
     background: none;
-    border: $nav-tabs-border-width solid transparent;
-    @include border-top-radius($nav-tabs-border-radius);
+    border: var(--#{$prefix}nav-tabs-border-width) solid transparent;
+    @include border-top-radius(var(--#{$prefix}nav-tabs-border-radius));
 
     &:hover,
     &:focus {
       // Prevents active .nav-link tab overlapping focus outline of previous/next .nav-link
       isolation: isolate;
-      border-color: $nav-tabs-link-hover-border-color;
+      border-color: var(--#{$prefix}nav-tabs-link-hover-border-color);
     }
 
     &.disabled {
-      color: $nav-link-disabled-color;
+      color: var(--#{$prefix}nav-link-disabled-color);
       background-color: transparent;
       border-color: transparent;
     }
@@ -63,14 +83,14 @@
 
   .nav-link.active,
   .nav-item.show .nav-link {
-    color: $nav-tabs-link-active-color;
-    background-color: $nav-tabs-link-active-bg;
-    border-color: $nav-tabs-link-active-border-color;
+    color: var(--#{$prefix}nav-tabs-link-active-color);
+    background-color: var(--#{$prefix}nav-tabs-link-active-bg);
+    border-color: var(--#{$prefix}nav-tabs-link-active-border-color);
   }
 
   .dropdown-menu {
     // Make dropdown border overlap tab border
-    margin-top: calc($nav-tabs-border-width * -1); // stylelint-disable-line function-disallowed-list
+    margin-top: calc(var(--#{$prefix}nav-tabs-border-width) * -1); // stylelint-disable-line function-disallowed-list
     // Remove the top rounded corners here since there is a hard edge above the menu
     @include border-top-radius(0);
   }
@@ -82,16 +102,22 @@
 //
 
 .nav-pills {
+  // scss-docs-start nav-pills-css-vars
+  --#{$prefix}nav-pills-border-radius: #{$nav-pills-border-radius};
+  --#{$prefix}nav-pills-link-active-color: #{$nav-pills-link-active-color};
+  --#{$prefix}nav-pills-link-active-bg: #{$nav-pills-link-active-bg};
+  // scss-docs-end nav-pills-css-vars
+
   .nav-link {
     background: none;
     border: 0;
-    @include border-radius($nav-pills-border-radius);
+    @include border-radius(var(--#{$prefix}nav-pills-border-radius));
   }
 
   .nav-link.active,
   .show > .nav-link {
-    color: $nav-pills-link-active-color;
-    @include gradient-bg($nav-pills-link-active-bg);
+    color: var(--#{$prefix}nav-pills-link-active-color);
+    @include gradient-bg(var(--#{$prefix}nav-pills-link-active-bg));
   }
 }
 
diff --git a/scss/_variables.scss b/scss/_variables.scss
index 482d9ca8e0..de1a871d3c 100644
--- a/scss/_variables.scss
+++ b/scss/_variables.scss
@@ -1252,7 +1252,7 @@ $card-group-margin:                 $grid-gutter-width * .5 !default;
 // scss-docs-start accordion-variables
 $accordion-padding-y:                     1rem !default;
 $accordion-padding-x:                     1.25rem !default;
-$accordion-color:                         $body-color !default;
+$accordion-color:                         var(--#{$variable-prefix}body-color) !default;
 $accordion-bg:                            $body-bg !default;
 $accordion-border-width:                  $border-width !default;
 $accordion-border-color:                  var(--#{$prefix}border-color) !default;
@@ -1265,7 +1265,7 @@ $accordion-body-padding-x:                $accordion-padding-x !default;
 $accordion-button-padding-y:              $accordion-padding-y !default;
 $accordion-button-padding-x:              $accordion-padding-x !default;
 $accordion-button-color:                  $accordion-color !default;
-$accordion-button-bg:                     $accordion-bg !default;
+$accordion-button-bg:                     var(--#{$variable-prefix}accordion-bg) !default;
 $accordion-transition:                    $btn-transition, border-radius .15s ease !default;
 $accordion-button-active-bg:              tint-color($component-active-bg, 90%) !default;
 $accordion-button-active-color:           shade-color($primary, 10%) !default;
@@ -1402,14 +1402,16 @@ $modal-content-box-shadow-sm-up:    $box-shadow !default;
 
 $modal-backdrop-bg:                 $black !default;
 $modal-backdrop-opacity:            .5 !default;
+
 $modal-header-border-color:         var(--#{$prefix}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;
 $modal-header-padding-y:            $modal-inner-padding !default;
 $modal-header-padding-x:            $modal-inner-padding !default;
 $modal-header-padding:              $modal-header-padding-y $modal-header-padding-x !default; // Keep this for backwards compatibility
+
 $modal-footer-bg:                   null !default;
+$modal-footer-border-color:         $modal-header-border-color !default;
+$modal-footer-border-width:         $modal-header-border-width !default;
 
 $modal-sm:                          300px !default;
 $modal-md:                          500px !default;
diff --git a/site/content/docs/5.1/components/accordion.md b/site/content/docs/5.1/components/accordion.md
index 535ae46b5a..ee906f686a 100644
--- a/site/content/docs/5.1/components/accordion.md
+++ b/site/content/docs/5.1/components/accordion.md
@@ -150,8 +150,16 @@ Omit the `data-bs-parent` attribute on each `.accordion-collapse` to make accord
 
 Please read the [collapse accessibility section]({{< docsref "/components/collapse#accessibility" >}}) for more information.
 
-## Sass
+## CSS
 
 ### Variables
 
+{{< added-in "5.2.0" >}}
+
+As part of Bootstrap's evolving CSS variables approach, accordions now use local CSS variables on `.accordion` for enhanced real-time customization. Values for the CSS variables are set via Sass, so Sass customization is still supported, too.
+
+{{< scss-docs name="accordion-css-vars" file="scss/_accordion.scss" >}}
+
+### Sass variables
+
 {{< scss-docs name="accordion-variables" file="scss/_variables.scss" >}}
diff --git a/site/content/docs/5.1/components/card.md b/site/content/docs/5.1/components/card.md
index 3effb21d00..22b413325c 100644
--- a/site/content/docs/5.1/components/card.md
+++ b/site/content/docs/5.1/components/card.md
@@ -722,8 +722,16 @@ Just like with card groups, card footers will automatically line up.
 
 In `v4` we used a CSS-only technique to mimic the behavior of [Masonry](https://masonry.desandro.com/)-like columns, but this technique came with lots of unpleasant [side effects](https://github.com/twbs/bootstrap/pull/28922). If you want to have this type of layout in `v5`, you can just make use of Masonry plugin. **Masonry is not included in Bootstrap**, but we've made a [demo example]({{< docsref "/examples/masonry" >}}) to help you get started.
 
-## Sass
+## CSS
 
 ### Variables
 
+{{< added-in "5.2.0" >}}
+
+As part of Bootstrap's evolving CSS variables approach, cards now use local CSS variables on `.card` for enhanced real-time customization. Values for the CSS variables are set via Sass, so Sass customization is still supported, too.
+
+{{< scss-docs name="card-css-vars" file="scss/_card.scss" >}}
+
+### Sass variables
+
 {{< scss-docs name="card-variables" file="scss/_variables.scss" >}}
diff --git a/site/content/docs/5.1/components/modal.md b/site/content/docs/5.1/components/modal.md
index 6facc239c5..d3e64a96ad 100644
--- a/site/content/docs/5.1/components/modal.md
+++ b/site/content/docs/5.1/components/modal.md
@@ -766,10 +766,20 @@ Another override is the option to pop up a modal that covers the user viewport,
   </div>
 </div>
 
-## Sass
+## CSS
 
 ### Variables
 
+{{< added-in "5.2.0" >}}
+
+As part of Bootstrap's evolving CSS variables approach, dropdowns now use local CSS variables on `.modal` and `.modal-backdrop` for enhanced real-time customization. Values for the CSS variables are set via Sass, so Sass customization is still supported, too.
+
+{{< scss-docs name="modal-css-vars" file="scss/_modal.scss" >}}
+
+{{< scss-docs name="modal-backdrop-css-vars" file="scss/_modal.scss" >}}
+
+### Sass variables
+
 {{< scss-docs name="modal-variables" file="scss/_variables.scss" >}}
 
 ### Loop
diff --git a/site/content/docs/5.1/components/navs-tabs.md b/site/content/docs/5.1/components/navs-tabs.md
index 7e2a20d7ac..81591013d3 100644
--- a/site/content/docs/5.1/components/navs-tabs.md
+++ b/site/content/docs/5.1/components/navs-tabs.md
@@ -304,10 +304,28 @@ Add dropdown menus with a little extra HTML and the [dropdowns JavaScript plugin
 </ul>
 {{< /example >}}
 
-## Sass
+## CSS
 
 ### Variables
 
+{{< added-in "5.2.0" >}}
+
+As part of Bootstrap's evolving CSS variables approach, dropdowns now use local CSS variables on `.nav`, `.nav-tabs`, and `.nav-pills` for enhanced real-time customization. Values for the CSS variables are set via Sass, so Sass customization is still supported, too.
+
+On the `.nav` base class:
+
+{{< scss-docs name="nav-css-vars" file="scss/_nav.scss" >}}
+
+On the `.nav-tabs` modifier class:
+
+{{< scss-docs name="nav-tabs-css-vars" file="scss/_nav.scss" >}}
+
+On the `.nav-pills` modifier class:
+
+{{< scss-docs name="nav-pills-css-vars" file="scss/_nav.scss" >}}
+
+### Sass variables
+
 {{< scss-docs name="nav-variables" file="scss/_variables.scss" >}}
 
 ## JavaScript behavior