CSS is hard

I'm mostly making this just to test out the blog feature, but needed something to talk about so hey, why not rant about how bad I am at CSS!
I asked someone for help and they sent me a link to a really good site that explains tons of things you can do with CSS and how to do them (thanks btw) but even so, I'm really bad at making a nice theme sobs. I like my current one but wanted something original, sadly a bunch of my CSS either didnt work or messed up.
https://cdn.discordapp.com/attachments/822188036464574474/823501136278323221/ajnm1n2p5i061-removebg-preview.png
Moral of the story, if you can give me tips and tricks on how to make a decent theme or can even make a custom one for me (no pressure!) then hmu :')