QR code page using grid

Went started to learn the tools, CSS has too many options or ways to do the same thing. I wasted a lot of time selecting "the best" way to do something simple.

Who do you choose the way to move forward without overthinking?

Which areas of your code are you unsure of? box-sizing: border-box;

Live Server extension on VSCode helps a lot to speed up the process. Are there any other tools that help to preview the results faster and better on multiple devices?