QR code component using flexbox

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

This is my first project completed. I have attempted to use semantic HTML and flexbox, any feedback to improve would be much appreciated.

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

Trying to size the project was most challenging. I tried to guess sizes, based on the example design file, so I'm guessing it wont be exact. any pointers on getting sizing right for future projects would be great.

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

Any feedback regarding semantics and accessibility would be great. Additionally any pointers regarding responsive CSS, for future projects would be much appreciated