Responsive challenge made by using basic HTML, CSS Flex and JS

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

I'm satisfied with the result but it took me more time than it should, I've gotta keep practicing so some things become automatic.

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

Guess the HTML looks a bit confuse, I did my best to make it work but didn't spend much time on making it look simpler...

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

If anyone has any type of tips, specially on the JS I'd appreciate it!