Navbar closes when link on it is clicked - I want it to stay open

I am using a navbar with divs, and have constructed a sidebar that pops out.

I want to build a secondary navigation off the main navbar, so that when you click one of the nav bar links, it triggers an interaction that pops out the submenu.

When I open the menu and click the item to trigger the sub menu to fly out, the sub menu does fly out, but the man nav menu automatically closes.

How do I prevent the main navbar from closing when an element within it is clicked?

Open menu and click “Clinical Solutions” to see what I mean. The black sub menu pops out correctly, but the main menu closes. I want it to remain open so that it looks like the sub menu is branched off it.