QR Code Challenge #1

First time with everything - from writing a code from scratch, to setting up a github and publishing. I found it difficult to decide my starting point, went in circles and wanted to jump back and forth between writing a single html line and jumping to css right away. And wanting to get it perfectly right the first time. Eventually, my goal changed to just completing it. I made it more complicated than it was.

I'm unsure on the sizing, feel like I need A LOT more practice with the sizing and desktop vs mobile flexibilities and thought it would come a little more naturally. Can the code be simpler?