diff --git a/module/doc/view/lefttree.html.php b/module/doc/view/lefttree.html.php
index 147ecfa6f3..2bc5a4b8d5 100644
--- a/module/doc/view/lefttree.html.php
+++ b/module/doc/view/lefttree.html.php
@@ -30,7 +30,7 @@
 .tree li.has-input {overflow: hidden;}
 .tree-text {margin-left: 5px; overflow: hidden;}
 i.btn-info, i.btn-info:hover {border: none; background: #fff; box-shadow: unset;}
-.tree-version-trigger {padding: 0 10px; width: 54px;}
+.tree-version-trigger {padding: 0 10px; width: 54px; border-radius: 5px; background: #F8F8F8;}
 
 /* css for sidebar */
 .sidebar-toggle {flex: 0 0 16px;}