While we're here, what are the top CSS or front end frameworks that are just static CSS files (maybe a single JS file too) that I can either download or hotlink

While we're here, what are the top CSS or front end frameworks that are just static CSS files (maybe a single JS file too) that I can either download or hotlink from a CDN? I usually fallback to bootstrap for personal projects or prototypes because it is as easy as including a CSS file and a JS file. No npm install or compile steps required.