@bobdobberson i would probably just make it a programmable typesetter, and give up on the failed ideas like html<>css. in practice, the html is married to the css. user styles don't *really* work, except to change a couple of basic colors and fonts.

so i would do something like SILE does where you lay out text boxes, and they flow in to one another, and just expose things like page sizes to the typesetter so when you resize the page it just retypesets the whole thing.