Add blending for dropdowns

core/css/buttons.css

@@ -237,6 +237,10 @@ button.formbutton a {
 	z-index: 10;
 }
 
+*.wdropdown.active > button {
+	border-bottom: none;
+}
+
 *.wdropdown.active > div.select {
 	display: inline;
 }