Frontend QR navigator using HTML and CSS

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

I manged to build this site in 15 min.There is probably alot of things that can be done much more better but I need to have more knowledge to be able to see what are things that I can improve on this challenge

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

I didn't understand how to set up page should I put specific width or height In the end I used dev tools to be able to see how it would be on big screens and how it looks on small screen and from design looks pretty correct.

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

Any kind of comment how to do or improve is great I love to learn alot about coding!