Add color-scheme mixin

scss/_mixins.scss

@@ -10,6 +10,7 @@
 
 // Helpers
 @import "mixins/breakpoints";
+@import "mixins/color-scheme";
 @import "mixins/image";
 @import "mixins/resize";
 @import "mixins/visually-hidden";

scss/mixins/_color-scheme.scss

@@ -0,0 +1,17 @@
+// scss-docs-start mixin-color-scheme
+@mixin color-scheme($name) {
+  @if $name == dark {
+    @media (prefers-color-scheme: dark) {
+      @content;
+    }
+  } @else if $name == light {
+    @media (prefers-color-scheme: light) {
+      @content;
+    }
+  } @else {
+    @media (prefers-color-scheme: #{$name}) {
+      @content;
+    }
+  }
+}
+// scss-docs-end mixin-color-scheme

site/content/docs/5.0/customize/sass.md

@@ -276,3 +276,25 @@ $border-width: 0;
   border-radius: subtract($border-radius, $border-width);
 }
 ```
+
+## Mixins
+
+Our `scss/mixins/` directory has a ton of mixins that power parts of Bootstrap and can also be used across your own project.
+
+### Color schemes
+
+A shorthand mixin for the `prefers-color-scheme` media query is available with support for `light`, `dark`, and custom color schemes.
+
+{{< scss-docs name="mixin-color-scheme" file="scss/mixins/_color-scheme.scss" >}}
+
+```scss
+.custom-element {
+  @include color-scheme(dark) {
+    // Insert dark mode styles here
+  }
+
+  @include color-scheme(custom-named-scheme) {
+    // Insert custom color scheme styles here
+  }
+}
+```