I am getting at least two origins e.g. settings.css?ver=771 or
If I switch into the CSS tab and open the location menu I see bunch of
included on the page.
Also, if I click on the blue link (in the Styles panel) it navigates
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
server side Firebug has no way to figure it out...