Wow, that's held up really well for being a couple of decades old. I really like the 2 column layout, makes it really easy to skim sections.
The format of your machine learning notes is also nice, I like the loose structure of it.
The colorscheme is also pleasant, nice to see something that isn't the typical light/dark mode, though you may want to change the color of your copyright notice though, it has very low contrast with the background.
It's the same look for a couple decades. Used to be HTML tables, currently responsive CSS (see the 3 simple width modes).
Generated by an ancient Emacs Lisp program.
The late '90s version kludged a color-coded two-level tab site-wide navigation scheme out of `table` elements, no images. The only remaining example (with tab text removed) is: https://www.neilvandyke.org/lab-linux-1999/