diff --git a/stylesheets/ui-variables.less b/stylesheets/ui-variables.less
index a5ecb7f..9db05c5 100644
--- a/stylesheets/ui-variables.less
+++ b/stylesheets/ui-variables.less
@@ -65,6 +65,9 @@
 @tree-view-background-color: @tool-panel-background-color;
 @tree-view-border-color: @tool-panel-border-color;
 
+@scroll-background: @background-color-highlight;
+@scroll-thumb: @overlay-border-color;
+
 @ui-site-color-1: @background-color-success; // green
 @ui-site-color-2: @background-color-info; // blue
 @ui-site-color-3: @background-color-warning; // orange