Include Open Sans font and some UI tweaks reducing white space in the editor. (#312)

theme/site/collections/menu.overrides

@@ -5,4 +5,9 @@
 
 .ui.menu.inverted .item {
     text-transform: uppercase;
+}
+
+#mainmenu {
+    background: #f4f7f9;
+    border-bottom: 5px solid #00a5c8;
 }