diff --git a/build/scss/_root.scss b/build/scss/_root.scss
new file mode 100644
index 000000000..4fb599623
--- /dev/null
+++ b/build/scss/_root.scss
@@ -0,0 +1,14 @@
+.dark-mode {
+  :root {
+    // Custom variable values only support SassScript inside `#{}`.
+    @each $color, $value in $colors-alt {
+      --#{$color}: #{$value};
+    }
+
+    @each $color, $value in $theme-colors-alt {
+      --#{$color}: #{$value};
+    }
+  }
+}
+
+//
diff --git a/build/scss/parts/_core.scss b/build/scss/parts/_core.scss
index 0dda2630a..123468e85 100644
--- a/build/scss/parts/_core.scss
+++ b/build/scss/parts/_core.scss
@@ -2,6 +2,7 @@
 // Part: Core
 //
 
+@import "../root";
 @import "../animation-effects";
 @import "../preloader";
 @import "../layout";