Filled square on current tab (div children of tab's link blocks)

Here is a read-only link to my website. I know, it’s a mess. It’s my second project on webflow so I will get better at organizing I’m sorry.

So I have a full page tab where I have all my content. However, I need the current tab to show a filled square (on the second nav on the top right) so you know where you are, and when you change tab the fill goes back to black. I just can’t make it work. I did some research and it looks like you can’t style the children of the tab’s link block when selected. I tried with interaction on tab click but if I do it this way, the squares are filled when I load the page, and they go back to black after I hover. Sometimes it does even get filled when you click on the tab. The interaction is very weird.

I know I shouldn’t leave this for last, but tomorrow is my final and if anyone could help me I would really appreciate it. Thank you.

TL;DR: Need my second nav (top right of the section) to indicate on what tab are you by showing the current with a filled square, and when you swap tabs it goes back to filled black and the current one gets filled with the corresponding color.