Responsive landing page (HTML-Flexbox)

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

UPDATED PROJECT

This was a tough project for me. I am a self taught developer, and this was my first time diving into a slightly bigger project. I definitely bit off more than I can chew with this one. I never had to deal with making bigger sites responsive, and with the design of the landing page I had to dig deep to make this site responsive. I hacked this site together, and did not quit. As I get more experience, I plan on coming back to this landing page and cleaning it up.

Update - I fixed all the mistakes and used a wonderful app (Shape Divider App) for the bottom curves. I also instead of guessing at the positioning I used the Google Dev tools to dial in the background patterns. I decided not be lazy and add ALL the media queries necessary for the landing page.

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

Background Image Positioning

Because I'm a newbie I completely disregarded the power of Google dev tools. I can't believe how much easier my coding experience was just by using the dev tools(click on the pointer and use the arrows to move background images/patterns around and update the css code). My advice to any newbie would be to not sleep on the Google dev tools, especially when dealing with background images/patterns.