The separation of concerns argument is dogmatic here. Just because it used to be that you should keep presentation in your CSS and behavior in your javascript, doesn&#x27;t mean that&#x27;s a universal truth. It&#x27;s a good abstraction to separate presentation from behavior, but that doesn&#x27;t mean one has to be done in one language and the other in a different one. Separating the concerns just by partitioning them within your codebase is just as good for organization.<p>There are two real reasons to use CSS for your styles. One is that your page should work without javascript, and doing your styles in javascript is a completely stupid reason to break support for no-javascript environments. The other is user choice. If a user doesn&#x27;t like something about how your page is presented, they can fix it using userstyles. Maybe some text is too small for them to comfortably read but when they zoom in the layout breaks or other text gets too big. It&#x27;s hostile to break this standard feature of the web just for whatever silly gains you get from doing your styles in javascript.