Any chance that this could be updated for the pro menu?
This members-only tutorial provides the steps to improve the appearance of Oxygen's Pro Menu's mobile inline dropdown items by bolding the top-level menu items, indenting the sub menus and adjusting the spacing.
Edit your Main Catch All Template having the sitewide header and footer.
Add a Pro Menu component where you want the menu to appear and select your menu.
You can either configure it from scratch or use a preset. In my test site, I selected "Desktop and Mobile".