QR Code Box: Rookie CSS, Questions Inside

Hello! This challenge is the closing to my intro to HTML/CSS. I'm preparing to dive deeper, so I have a few questions about the simple stuff that might be overlooked otherwise:

1. I used element width to "squeeze" the text elements to match the provided design. Is there a better method to match wrapping or is element width the way to do it?

2. I used absolute positioning to roughly estimate the center position of my screen. What is the recommended method to center non-text elements? I have yet to learn responsive design, so maybe that's where the answers to this question are.