QR code round 2

Actually, i'm having a problem to center a div, that's why I try to make myself another try. When I looked at others solution I was impressed and sad at the same time. But on the other hand, I learned from my mistakes although this 2nd try is still not perfect but it looks much better than my 1st try. So, if you guys have advice or see any mistakes on my code just tell me, I'll appreciate it and consume it to make me a better in coding.