Your styles are coupled to your UI logic anyway, even if you go out of your way to make them implicit by separating the CSS and JS into their own files. It's be

Your styles are coupled to your UI logic anyway, even if you go out of your way to make them implicit by separating the CSS and JS into their own files. It's better to have the relationship explicitly defined in code instead of hiding it. That's the whole reason why CSS sometimes breaks in unexpected ways: you fail to realize the implicit coupling of the styles and the UI logic, so you fail to reason what changes need to be made both to styles and the UI logic to make your change.