How to arrange such a menu?

Question

css

Hello. Immediately I ask you not to scold me for the code, I'm just a beginner coder.
That's how I started the implementation of this menu, but now I doubt if I'm doing it right or can it be somehow easier and faster?
Plus, there were difficulties with styling the active menu item and submenu.
I ask knowledgeable people to help/correct my code.

https://jsfiddle.net/hrn4bwe0/