So since you need javascript anyway...
http://www.javascript.tech.xirium.com/babelparam/
user-selectable page styles using javascript, using appended
parameters to reload the page. (writing inline comments to create a
virtual outline or change the language of the page is also a neat
trick; the FAQ collapses.)
It's completely over the top; after all, you could simply
document.write() the header line loading in a style sheet instead,
since you require javascript on to see style sheets anyway. But that
would make page decoration like WorkBench3.0 or Calypso tricky to
implement.
L.
<L.Wood@surrey.ac.uk>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>