Interactive Connect Four with custom UI, and computer play

So I made this Connect Four before I realized there was a challenge on Frontend Mentor but I still figured it would be useful to post it for some feedback and general advice.

This was one of my first in depth projects that included different JS techniques and I had a lot of fun learning ways to make this work. One of the more interesting aspects was figuring out how to make the computer actively play and block moves without making it impossible to win