QR Code Component Responsive Card Solution using HTML and CSS

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

I'm proud that I remembered a good majority of HTML and CSS. I'm also proud of the new knowledge I learned while doing this project. I was able to learn how to do calculations from PX or VH and EM, and I learned that browsers take more kindly to EM or VH for sizing.
What I would do differently, is that I would make sure I didn't have the class tag set for things that did not need it in order to get the proper sizing earlier on.

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

The challenges I encountered at first had to do with the sizing with using PX, hence me learning about how browsers prefer something OTHER than PX for sizing. Another challenge I encountered was trying to view the code for the designs. The site suggested would not allow me to see it all for free so I had to find a different way to view it.

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

Personally I just want whatever feedback you may have. I am always up for some educational information. How could I have done better? What did you like/dislike and why? Is there something I could have done differently? Do you have a referral for a place that could teach me new tips and tricks for better results?