How does it compare with vue.js? I never worked with any modern JS framework like this but on paper I did not like writing CSS in javascript and vue.js had a normal way to write CSS and to me it looked superior in other ways as well.

https://github.com/styled-components/styled-components

Edit: for the record there's nothing stopping you from using CSS files with classnames on your tags as usual, but libraries like styled-components allow you to easily scope and collocate your CSS with your components.