I am getting at least two origins e.g. settings.css?ver=771 or
style.css.php?ver=20121225
If I switch into the CSS tab and open the location menu I see bunch of
CSS files
included on the page.
Also, if I click on the blue link (in the Styles panel) it navigates
me to
the target CSS file in the CSS panel.
Note that Firebug is operating on objects in the browser and
it has no idea about the server side technology.
So, if the CSS files are somehow dynamically computed and generated
on the
server side Firebug has no way to figure it out...
Honza