root color for dark mode

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};
+    }
+  }
+}
+
+//

build/scss/parts/_core.scss

@@ -2,6 +2,7 @@
 // Part: Core
 //
 
+@import "../root";
 @import "../animation-effects";
 @import "../preloader";
 @import "../layout";