QR Code Challenge using HTML and CSS

A little bit of background: This is my very first challenge in Frontend Mentor; I picked up HTML and CSS through a Udemy course last year, and currently I am studying React.js. Along the way, I realized nothing is getting internalized, as I am slowly forgetting all the basics and foundations of HTML, CSS, and JS. That is why I wanted to revisit these techniques first before I move on with the rest of React.js.

As I was working on this first challenge, I realized I did not remember the simplest thing, such as positioning and centering. There are repeated elements in CSS that need grouping but somehow doing that messes up the project. So I am submitting a rough and raw version of this challenge, to see how my first step in working on an actual project is.

Any feedback would be appreciated. Thank you.