diff --git a/common/_static/custom.css b/common/_static/custom.css
index 4b15ea44d7..73dfaa1d96 100644
--- a/common/_static/custom.css
+++ b/common/_static/custom.css
@@ -17,6 +17,7 @@ h1, h2, h3, h4, h5, h6, legend {
 
 .wy-nav-side {
     background: #ddd;
+    overflow-y: auto;
 }
 
 .wy-side-nav-search {
@@ -145,4 +146,4 @@ h1, h2, h3, h4, h5, h6, legend {
 .btn-neutral:hover {
     background-color: #0054a3 !important;
     color: #fff !important;
-}
\ No newline at end of file
+}