diff --git a/panel/template/fast/css/fast_root.css b/panel/template/fast/css/fast_root.css
index e953c0ec4e..0adcf0f757 100644
--- a/panel/template/fast/css/fast_root.css
+++ b/panel/template/fast/css/fast_root.css
@@ -1,4 +1,7 @@
 /* fast_root.css */
+:root {
+  --track-width: 2;
+}
 #menu * {
   width: 100%;
 }