If you need caching then you would likely server render your page and that would inline all of the critical css to be cached as well. Writing your css in JS fi

If you need caching then you would likely server render your page and that would inline all of the critical css to be cached as well. Writing your css in JS files also does nothing to prevent you from separating content and presentation. You can write components that just handle styling. I see more problems with separation in css where you end up with one giant file that handles the whole site.