It wouldn't be a separate language. Bake it into js.
Also selectors being global by default is a flaw.
Bake it into js? NOPE. Separation of concerns is great. Put layout into the a new FLOW language, style into CSS, and actions into JS or web assembly.
You can separate concerns within the same language... look at all other "ui languages". Web dev is the only arena (correct me if I'm wrong) where you need 3 languages (html/css/js) to make a modern day component.
Mobile dev has fewer issues and has separation of concerns with no problem. If you used any preprocessor (less/sass) or template lang (handlebars, etc...) you proved my point. We wouldn't need that if js was the single language. This is one of the reasons why react is so popular.
Before I come off as someone who hates css, I use to only write html/css and hated js. Times have changed.
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