diff --git a/scss/core/_variables.scss b/scss/core/_variables.scss
index 4380ac69..7bc7d759 100644
--- a/scss/core/_variables.scss
+++ b/scss/core/_variables.scss
@@ -106,6 +106,7 @@ $color-base:                 $color-black-light;
 $color-focus:                $color-gray-light;
 $color-visited:              $color-purple;
 
+$color-overlay:              rgba(#000, 0.5);
 $color-shadow:               rgba(#000, 0.3);
 $color-transparent:          rgba(#000, 0);