Looking for definition and guidelines for designing classic/abstract/flat design? [closed]

Looking to build my personal portfolio I am looking for names and guidelines of abstract/flat/classic style UI. I'm trying to design a "nostalgia" feeling of 90's-00's with a modern twist.

The best example I could find is: https://glitch.com/, also Microsoft fabric and ant design have a feel but not pinpointed to what I need.

The main feature is simplicity, text-oriented/typography, low animation smoothing.