Thx for the extra posts. They show just how complicated the variations are. I think allowing a user to set values would make things even more complicated as then you have the whole units thing - em, in, pt, px, % etc.
So what is the difference between @page and body anyway? How do they relate?
I'll be honest, my enthusiasm for this has always been lukewarm for this as in editing hundreds of ePubs I haven't once hit one that needed this. If it was trivial then I would jump in and add it, but I think the examples above show it isn't.
If someone else is prepared to knock up the Python code I will happily make the effort to integrate it. Just write a function assuming you have the contents of a CSS file as input and I can take care of the rest, either PM it to me or post it here...