Atomic CSS is not ideal for performance. No tooling can extract the per-page critical CSS, so you end up shipping more CSS to the browser than necessary. The bigger and more dynamic the app, the more unnecessary code you will ship.
Isn’t this solved by using PurgeCSS? During your build phase it removes any unused classes from the final build. You end up with a single CSS file, which is usually quite small, that your browser only downloads once and then caches it.
Do people actually generate a CSS file for every page?
Do people actually generate a CSS file for every page?