You'd probably like Clojure.

As an aside, though, part of the reason we have different languages for things like backend code, markup and styling is that they're commonly done by different people with different specialties. A general-purpose language will not offer much benefit to a designer, but it will trip them up more often. Having a language tailored to your specialist is a good thing. The only time you'd really want everything done in one language is when the same coders are doing everything. I admit I'm in that situation very often, but it's more maintainable if you just use CSS or similar so that normal front-end guys can work with it.

That makes sense. Ideally it would be nice to have one common elegant language which can do it all. But I doubt that any one language can do everything elegantly. The syntax of some languages make them much more elegant for certain purposes. For example compare XML and JSON. JSON is great as a lightweight way to represent simple objects, but XML is better for representing entire HTML documents. Likewise you can do all your CSS stuff by manipulating DOM properties in JavaScript, but pure CSS is a cleaner and more readable way to do things because it only does styling statements. (Unless you go out of your way to put logic into your CSS.)

The bigger the project is the more you have to favor readability and maintainability first, and using multiple specialized languages to accomplish different specific tasks is an effective way to keep the codebase readable and maintainable.