Did you ever develop with Flex? MXML and CSS + ActionScript was a great way to design webapps, and if phones actually ran flash, apps and components could be just as responsive as anything modern. The closest JS ever got to it was Angular 1, but then the Angular folks changed course and whatever version it's at now is very different.

My current favorite is the ClojureScript ecosystem, but it's even more different than either still, and really only suited for apps. For a plain old website composed of several pages, mostly static content, it's hard to beat plain old HTML with maybe a light sprinkle of JS for a couple things.