Fix ad/menu issue

Fix #9

Change-Id: I75ad43c9f502d6c494d7883c89026049df5bd0a6
(cherry picked from commit 7e610a50dd02a13c55cb79e78f7612e49f248e40)
diff --git a/_sass/_layout.scss b/_sass/_layout.scss
index def56f8..2d15fb3 100644
--- a/_sass/_layout.scss
+++ b/_sass/_layout.scss
@@ -49,6 +49,7 @@
         border: 1px solid $grey-color-light;
         border-radius: 5px;
         text-align: right;
+        z-index: 1;
 
         .menu-icon {
             display: block;