fixed navigation bar positioning

[Stefan Kost <ensonic hora-obscura de>]

hi,

I've played a bit around with css to make the top and bottom navigation bar of 
gtk-doc sticky. It works in devhelp and in the browser.

The trick is to use to the top-nav:
  position:fixed;
  top:0px;
and for the bottom-nav
  position:fixed;
  bottom:0px;

Further the content needs somthing like
  margin-top:5em;
  margin-bottom:2em;

The problems are
* determining the size of the margins
* the content shines thrugh the margins of the top and bottom nav

The latter can be 'fixed' by dropping the space around the nav-bars.
Any comments? Would you want that in gtk-doc?

Ciao
  Stefan