Responsive design using flexbox and grid

What are you most proud of, and what would you do differently next time?

I'm mostly proud of my implementation of the site's functionality in javascript and its responsiveness. However, I'm not sure if the way I went about them was the best or if it was either faulty or overly complicated.

What challenges did you encounter, and how did you overcome them?

I overcame so many challenges in javascript, I can't even list them all. That much is obvious from the abundance of comments across the code. I have programming experience, but It's my first time using javascript so I'm generally pretty proud of my handling every problem I ran into though I think I cut some corners that shouldn't be cut.

What specific areas of your project would you like help with?

Any advice at all on how I can improve would be much appreciated. Even if its just a way I could have done the same thing easier.