Do not lay the transparent hint mirror over underlying menu items

Change-Id: Ie7096ecc31871d2a05a49248baf9eefbc68d0e85
diff --git a/dev/scss/header/hint.scss b/dev/scss/header/hint.scss
index 8c6c329..68222b7 100644
--- a/dev/scss/header/hint.scss
+++ b/dev/scss/header/hint.scss
@@ -68,6 +68,8 @@
     opacity:     0;
     white-space: pre-wrap;
     overflow:    hidden;
+    display:     inline-block;
+    height:      0;
   }
 
   // TODO: Only in focus