Sorry if I wasn’t clear. I didn’t mean “Make it work with HTML and CSS today”. I meant, Why couldn’t HTML and CSS be used as a basis for a PDF-like format? New features are constantly being added to HTML and CSS. In 5 to 10 years, maybe we’ll have a revamped powerful paged layout that will have all the features that you mentioned.

So my point is, why create a new format when you can enhance HTML and CSS?