diff --git a/src/themes/default/globals/site.variables b/src/themes/default/globals/site.variables
index 6b9b33de6..dce24400e 100644
--- a/src/themes/default/globals/site.variables
+++ b/src/themes/default/globals/site.variables
@@ -374,6 +374,9 @@
     Derived Values
 --------------------*/
 
+/* Rendered Scrollbar Width */
+@scrollBarWidth: 15px;
+
 /* Header Spacing */
 @headerLineHeightOffset : (@lineHeight - 1em) / 2;
 @headerTopMargin        : ~"calc(2rem - "@lineHeightOffset~")";