diff --git a/core/css/header.scss b/core/css/header.scss
index 42f64a42edc..1d4009a7ae6 100644
--- a/core/css/header.scss
+++ b/core/css/header.scss
@@ -224,7 +224,7 @@ nav {
 		position: absolute;
 		pointer-events: none;
 		border-color: rgba(0, 0, 0, 0);
-		border-bottom-color: rgba(255, 255, 255, .97);
+		border-bottom-color: $color-main-background;
 		border-width: 9px;
 		margin-left: -9px;
 	}