QR Code using flexbox

I found it difficult/intimidating to make the page properly viewable on mobile. My main concern is that, when my page is viewed from the devtools mobile viewport on Firefox, the screen height is needlessly big and requires unnecessary scrolling to view the QR code properly. I ended up reaching out to a friend who is more experienced in coding than I, and he assured me that the page would be properly viewable on an actual phone screen.

What I'd like feedback on is whether I succeeded in making the page comfortably viewable on mobile, and if my friend is correct about viewing it by phone.

Thank you so much :)