I was like you until about a year or two ago, and then set out to learn it enough to implement a site layout without having to resort to copy and pasting things I don't understand.

It wasn't that hard, once you accept that it'll require it's own study and practice. I put in maybe 20 hours dedicated study and got a lot better out of it.

I did a few video courses on LinkedIn Learning (formerly Lynda.com) through my public library. I did a general CSS course and a flexbox CSS course. Then I set out to design pages I needed without pulling some random blog theme and calling it a day.

I've gotten a bit better at design as well, although it is a much intrinsic field than CSS and requires a lot more study. The biggest difference was once I treated the design stage with respect as its own discipline and started designing in a design tool (figma) instead of "doing it live" by trying to tweak the design in code as I went. It made me 100% focused in that stage at the design problems and the feedback loop got a lot tighter compared to editing and running code to see how it looked.