Fix 'menu below hint marker' bug

Change-Id: Id9806b5152c84bd0ddd86ba9ed0bcc1996a0fecf
diff --git a/dev/scss/base/menu.scss b/dev/scss/base/menu.scss
index b743362..4f76683 100644
--- a/dev/scss/base/menu.scss
+++ b/dev/scss/base/menu.scss
@@ -60,6 +60,7 @@
       color: transparent;
       width: $border-size;
     }
+    overflow: hidden;
     padding: $item-padding;
     padding-top: 0;
     padding-bottom: 0;