🔥CSS in CSS (e.g. Sass) 🔥CSS in JS (e.g. Styled-components) 🔥Utility-first (e.g. Tailwind)
And since we are entering a hugely opinionated area here, I am gonna throw a holywar trigger and tell you that: although I'm using Sass at work, I am in absolute love with Styled-components, if approached properly, the readability of your code is sooo good.
On the other hand, Tailwind, although with a clear purpose, seems to be the most ugly when it comes to readibility. The whole purpose of separate files for styling was to avoid having them in you main component (and not throw them inside your component as a never ending style line🤷♂)