Fix Sass compilation breaking change in v5.3

scss/_variables.scss

@@ -1745,3 +1745,5 @@ $kbd-bg:                            var(--#{$prefix}body-color) !default;
 $nested-kbd-font-weight:            null !default; // Deprecated in v5.2.0, removing in v6
 
 $pre-color:                         null !default;
+
+@import "variables-dark"; // TODO: can be removed safely in v6, only here to avoid breaking changes in v5.3

scss/tests/mixins/_color-modes-non-breaking.test.scss

@@ -0,0 +1,71 @@
+// TODO: this file can be removed safely in v6 when `@import "variables-dark"` will be removed at the end of _variables.scss
+
+// stylelint-disable selector-attribute-quotes
+
+@import "../../functions";
+@import "../../variables";
+// Voluntarily not importing _variables-dark.scss
+@import "../../maps";
+@import "../../mixins";
+
+@include describe("global $color-mode-type: data") {
+  @include it("generates data attribute selectors for dark mode") {
+    @include assert() {
+      @include output() {
+        @include color-mode(dark) {
+          .element {
+            color: var(--bs-primary-text-emphasis);
+            background-color: var(--bs-primary-bg-subtle);
+          }
+        }
+        @include color-mode(dark, true) {
+          --custom-color: #{mix($indigo, $blue, 50%)};
+        }
+      }
+      @include expect() {
+        [data-bs-theme=dark] .element {
+          color: var(--bs-primary-text-emphasis);
+          background-color: var(--bs-primary-bg-subtle);
+        }
+        [data-bs-theme=dark] {
+          --custom-color: #3a3ff8;
+        }
+      }
+    }
+  }
+}
+
+@include describe("global $color-mode-type: media-query") {
+  @include it("generates media queries for dark mode") {
+    $color-mode-type: media-query !global;
+
+    @include assert() {
+      @include output() {
+        @include color-mode(dark) {
+          .element {
+            color: var(--bs-primary-text-emphasis);
+            background-color: var(--bs-primary-bg-subtle);
+          }
+        }
+        @include color-mode(dark, true) {
+          --custom-color: #{mix($indigo, $blue, 50%)};
+        }
+      }
+      @include expect() {
+        @media (prefers-color-scheme: dark) {
+          .element {
+            color: var(--bs-primary-text-emphasis);
+            background-color: var(--bs-primary-bg-subtle);
+          }
+        }
+        @media (prefers-color-scheme: dark) {
+          :root {
+            --custom-color: #3a3ff8;
+          }
+        }
+      }
+    }
+
+    $color-mode-type: data !global;
+  }
+}