Small icon & math icon styling

services/web/public/stylesheets/app/editor/toolbar.less

@@ -293,6 +293,15 @@
 .formatting-icon {
 	font-style: normal;
 	line-height: 1.5;
+
+	&--small {
+		font-size: small;
+		line-height: 1.9;
+	}
+
+	&--serif {
+		font-family: @font-family-serif;
+	}
 }
 
 .formatting-more {