I know absolutely nothing about CSS.
My very first webpage was coded in straight HTML (as is my current homepage), and when I decided I wanted something fancier, WYSIWYG editors were becoming popular, so I sort of skipped over the whole "learning css" thing.
This blog is "powered by DotClear" which offers a simple way to import "themes". The Themes actually provide the color themes and the structure of the blog. The theme I'm using here is called "atopa", but I wanted something a little bit different. I poked and prodded around in the mysterious stylesheet code, made some educated guesses, and ended up with what you see now. It's inspired by the color scheme of the Counter Strike mod for the first Half Life game. In addition to being a mod I played a ton when it came out (20 years ago, oh my!), I also just enjoy the subdued earthy tones (my closet is full of greens, browns, tans, and greys), and I find that it's easier on the eyes than bright white, while still being more colorful than the typical "dark mode" website. I also tweaked the spacing a bit, since I felt that the default spacing squished all of the content into the middle of the screen and left huge empty gaps on each side.
Anyway, if you don't like the colors, this blog is also available via RSS feed and gopher, both of which will leave the coloring up to the client you're using.