Well, I don't use Firebug. I am old-fasioned, so I debug by looking at the code
For starters, go through the list at http://validator.w3.org/check?uri=http%3A%2F%2Faone.lk%2Fdemos%2Fpc_detail.php%3Fpcid%3D31&charset=%28detect+automatically%29&doctype=Inline&group=0
You should also change your DOCTYPE to strict, rather than transitional. And ideally to HTML 4.01 too, but that's a different story intirely, and XHTML 1.0 Strict will do for all practical purposes.
Specifically, you have a problem here:
You don't have a closing
>. While this is technically valid in HTML, it's invalid XHTML, and in either case you shouldn't rely on it HTML, as no commercial browsers support it.