diff --git a/site/theme/static/toc.less b/site/theme/static/toc.less
index faaec1cf97..09638e413f 100644
--- a/site/theme/static/toc.less
+++ b/site/theme/static/toc.less
@@ -54,6 +54,7 @@
   color: #aaa;
   font-size: 12px;
   margin-top: -4px;
+  background-color: #fff;
   a {
     padding-left: 8px;
     display: block;