diff --git a/app/assets/stylesheets/pages/issuable.scss b/app/assets/stylesheets/pages/issuable.scss
index d9218e15095..68a26e42b64 100644
--- a/app/assets/stylesheets/pages/issuable.scss
+++ b/app/assets/stylesheets/pages/issuable.scss
@@ -128,6 +128,7 @@
   top: 58px;
   bottom: 0;
   right: 0;
+  z-index: 10;
   transition: width .3s;
   background: $gray-light;
   padding: 10px 20px;