Since I've started authoring css, I've been asking myself and other css developers the same question: What is 'good css?'
After many years of writing, refactoring, and deleting css; this is a short list of things I believe to be true.
Doesn't break any functionality of plain html.
Makes an interface more readable for everyone on any device.
Enhances the usability and accessibility of an interface on all devices for all users.
Allows you to quickly change a single interface without breaking other interfaces.
Renders quickly in the browser.
Runs at 60fps (no jank on window resize or during scrolling).