> Also, with css in js I believe that pseudo elements and animations are an issue Here you might be remembering a particular, older technique known as "inline

> Also, with css in js I believe that pseudo elements and animations are an issue Here you might be remembering a particular, older technique known as "inline styles." This is probably the oldest CSS-in-JS technique, and has greatly fallen out of favor. Modern CSS-in-JS doesn't use that method anymore, and can do everything that normal CSS can do (in part because it really is just generating real CSS). So pseudo elements, media queries, animations etc. are no problem. :)