要不直接看官方的说明吧，https://tailwindcss.com/docs/utility-first ，刚开始看着是不容易接受，但是用起来真香。
>>> This approach allows us to implement a completely custom component design without writing a single line of custom CSS.

Now I know what you’re thinking, “this is an atrocity, what a horrible mess!” and you’re right, it’s kind of ugly. In fact it’s just about impossible to think this is a good idea the first time you see it — **you have to actually try it**.

But once you’ve actually built something this way, you’ll quickly notice some really important benefits:

- You aren’t wasting energy inventing class names. No more adding silly class names like sidebar-inner-wrapper just to be able to style something, and no more agonizing over the perfect abstract name for something that’s really just a flex container.
- Your CSS stops growing. Using a traditional approach, your CSS files get bigger every time you add a new feature. With utilities, everything is reusable so you rarely need to write new CSS.
- Making changes feels safer. CSS is global and you never know what you’re breaking when you make a change. Classes in your HTML are local, so you can change them without worrying about something else breaking.