Something is wrong with this picture.
Either you have separation of data and presentation or you don't. HTML didn't. HTML5 still doesn't. It is not possible to present an arbitrary block of data in a normalized, optimal form, and have CSS render it any way you want. For that you need script (or XSLT!), but even then, unless you go canvas, you have to deal with a markup language for presentation that is actively trying to not be presentation but be data instead. Its trying and failing. Life would be so much easier (and involve much less cognitive dissonance) if the DOM stuck to being presentation.<p>As it is, developing web apps is this giant joke, where you encrypt what you really want to happen in the form of pseudo-data (html) and magic rule-based transformation (css), and then the browser goes to a ton of effort to attempt to recreate what you really wanted. The effort the browser has to go through as soon as you introduce a div, or change its class, just to determine which, if any, of the CSS rules now apply to that node and any of its children, is just offensive. Worse: its something you, the programmer, must be able to model in your head to determine what the fuck is going on. Good luck with that! The result we get is "try it and see" "programming".<p>HTML1.0 was a local optimum. Somewhere there is another, better optimum. The W3C appears to be willing to travel the Himalayas of suboptimal to find it.