Fix layouting errors in a various modals

Fixes css problems in the theme modals, the user modals
and probably various others.

Fixes #1152

Author: Arnei

src/styles/mixins/_mixins-bourbon.scss

@@ -1,7 +1,7 @@
 // Bourbon leftovers
 
 @mixin clearfix {
-  .element::after {
+  &::after {
       clear: both;
       content: "";
       display: block;