Small fix of the header

It is necessary to have no spacing between the header and the main
content of the page.

Author: birdofpreyru

assets/css/layout/header.scss

@@ -183,6 +183,7 @@
 }
 
 .user-menu {
+  max-height: 54px;
   .user-avatar {
     height: 31px;
     width: 31px;