diff --git a/frontend/src/css/markdown-viewer/markdown-editor.css b/frontend/src/css/markdown-viewer/markdown-editor.css
index a3d732208f..edd8151ecd 100644
--- a/frontend/src/css/markdown-viewer/markdown-editor.css
+++ b/frontend/src/css/markdown-viewer/markdown-editor.css
@@ -49,11 +49,14 @@
   width: 260px;
   position: fixed;
   top: 68px;
-  overflow-y: auto;
+  overflow-y: hidden;
   right: 5%;
   z-index: 1;
   height: 80%;
 }
+.seafile-md-viewer .seafile-editor-outline:hover {
+  overflow: auto;
+}
 .seafile-md-viewer .seafile-editor-outline .active {
   color: #eb8205;
   border-left: 1px solid #eb8205;