diff --git a/docs/custom.css b/docs/custom.css
index 07ee64d61..0cd0ba4b5 100644
--- a/docs/custom.css
+++ b/docs/custom.css
@@ -14,6 +14,10 @@ pre {
     padding: 5px 10px;
 }
 
+div.topic {
+    background-color: #FAFAFA;
+}
+
 li a.current {
     font-weight: bold;
     border-bottom: 1px solid #000;