Copy designs you like, and keep a couple of CSS files +/- web components that you can carry along with you from project to project. Tweak then as you go.
Like everything else, getting good at making designs that you like will take time and effort, so if you want you get good at it, do it! I find it fun, and my designs aren't to everyone's taste (I too like black tshirts), but whatever.
Plus, getting good at making designs that i like has made me better at making designs clients/projects will like, so, win/win.
HTML is pretty straightforward so just understanding the very basic stuff is probably all you need. CSS is where html gets any challenge it might have.
CSS is weird because it's very "easy" so "real developers" kind of object to learning it, but the truth is, if you gave any of them a layout design, they probably couldn't build it. There are tools like tailwind to help, but, IMO, tailwind just helps you avoid learning css's vocabulary, but you just replace it with having to learn tailwind's vocabulary.
JavaScript on the other hand is a "real" programming language, though decidedly quick-n-dirtier than other languages. It lets you be a lot more sloppy. (Tbh it's a lot more forgiving than css!). As a result, it lacks the elegance and control that "real developers" like -- and, as most people's first language, it lets newcomers get into bad habits. For these reasons, JavaScript is a bit derided -- but, unlike CSS, most developers can't avoid it.
There are a few key ideas in JavaScript that, once you understand them, things make a lot more sense. (I won't get into them now, since it doesn't sound like you're at the point where that kind of clarity would help, but, when you are, come on back here and make a post!)
TLDR: HTML is definitely something you can just pick up along the way. JavaScript is a real language that will take a little while to feel comfortable with, and it will take a career to master. CSS will never be easy, so don't let it hold you back.