The joy of personal projects is they can look like shit! You'd also be surprised how much you can learn by just screwing around with something for a day. A big part of the whole exercise for me was getting out of my comfort zone and learning that I can learn. I'm primarily backend as well, and came up through the ops side (as opposed to formal CS), which always led to a lot of imposter syndrome, so a lot of the benefit came from just putting myself in an uncomfortable position and just staying there long enough to work my way through it.
That said, my goal for this was to wear the hair shirt (and also this was before GenAI was really a Thing) - if you just want to make something neat, absolutely vibe your way there.
But I don't want them to look like shit.
When I have gen AI create a starting point for the CSS for me, I still go over every line, and I always have to do a bunch of fixes and edits to get this to look how I want. Frankly, dicking around with the esotera of CSS is something I absolutely don't want to do and don't care about - it's really just reminding me of syntax that I forget because I don't do it often enough. This is also why I find gen AI invaluable for shell scripting. Hunting through reams of man pages doesn't make me learn any faster than just looking at the specific arg flags gen AI outputs (and potentially asking AI more about the details of that command). I just don't do enough shell scripting to really remember the command/arg specifics long term for things I don't commonly do.