Merge branch 'alert-bg' into 'develop'

38c3 Design: HIntergrund für Banner-Notifications setzen

See merge request hub/hub!1088

src/plainui/styles/themes/38c3.scss

@@ -17,3 +17,7 @@ body {
   background-image: url("38c3/img/grid-12x16.svg");
   background-repeat: repeat;
 }
+
+.hub-alert {
+  background-color: $black;
+}