Interestingly, PDFs actually do contain an embedded programming language in them, a subset of PostScript. [1] PostScript, meanwhile, is actually Turing complete with conditionals and loop structures inside of it. [2] I'd argue that makes PDFs a whole lot more programming language-y than CSS or XML.

[1]: http://en.wikipedia.org/wiki/PDF#Technical_foundations

[2]: http://en.wikipedia.org/wiki/PostScript#The_language