Based on what you've said, you're right, you don't understand it...the things you're comparing it to don't really make sense. Bem doesn't make sense to compare and neither do css modules. Tailwind is a stylesheet with css classes that do atomic things like changing border radius. It gives you a set of classes that allow you to build just about anything you need with just classes. When you compile an app that uses tailwind, it takes just the styles you use and puts them into a single stylesheet. So all of the things you claim to be wrong with tailwind aren't true. Tailwind is very performant because you only use the styles you need. It uses css variables for theming so there's no need to implement it in userland. It also uses css variables to do transforms which is very important because transforms are not additive in css yet. Even if you don't end up liking tailwind, the thing is executed really really well from the ground up.