Flexbox Mania - Clipboard Landing Page Project

On the first run through I got the mobile version looking great (without figma because I didn't pay for Premium, yet), however I made the mistake of not taking the desktop version into account when I got the layout set up. The result quickly became a complicated mess with special classes and cases all over the CSS document.

I learned that sometimes (read: a lot of the time) flex-boxes are a great tool to utilize for responsive layouts and there's not necessarily anything wrong with nesting them to get things working correctly.

Any feedback is always appreciated! I'm working on improving my self-taught skills in front-end development to set myself up for a career in web development when I leave the US Army in about a years time. So any tips, hints, resources, etc. that you feel like throwing my way will be greatly appreciated. Cheers!