Responsive QR code component using Flexbox

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

Haven't used a shadow box yet, I had to look it up on MDN web docs to make sure I was handling it correctly 😅

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

I defined my colors as CSS variables in the body{} section, is there a more traditional way to assign 'changing' variables in CSS - or is this the way to go?