I made a webpage to play with, and I've made a few
commits. Try poking around the github interface,
running git log, running git checkout <commit-hash> using a hash (the first 6 characters
are usually enough) copied from the git log.
It's common for a repo to have instructions for running a project locally or deploying a production instance. This one is just a single html page that imports a single css page, so there's not really anything to set up!
If you don't already have a preferred tool for a local
development server for static sites, I recommend using
live-server from npm. Install npm and then run npx live-server /path/to/repo, which will host the site
on 127.0.0.1:8080 and live-reload it when you change
the files!