Move contrast colors to color-definitions

src/_color-definitions.scss

@@ -577,3 +577,7 @@ $color-white: "255,255,255";
 
 /* colors.scss */
 $styleguide-generate-template: false !default;
+
+// The two possible colors for overlayed text.
+$color-dark-contrast: $color-white !default;
+$color-light-contrast: $color-black !default;

src/_variables.scss

@@ -71,10 +71,6 @@ $performance_font: 'Helvetica', 'Arial', sans-serif !default;
 
 /* ==========  Color & Themes  ========== */
 
-// The two possible colors for overlayed text.
-$color-dark-contrast: $color-white !default;
-$color-light-contrast: $color-black !default;
-
 // Use color primarily for emphasis. Choose colors that fit with
 // your brand and provide good contrast between visual components.
 $color-primary: $palette-indigo-500 !default;