How to make submenu items of a parent menu item

I have a parent menu item called “Graphic Design” and I want to put submenu items under this menu item so when people click on those project links, that “Graphic Design” menu item will still be underlined. Right now, the menu link is only underlined when I go to the Graphic Design menu item itself and not if I view any of those projects. I’m building this out manually since I don’t have the CMS version of webflow.

Any idea on how to do this?