bibliography entries from LyX

Hi there,
I'm not particularly good at CSS or XHTML, have the following problem:
I export my book with LyX to XHTML.
Bibliography labels show as
[number] entry
by means of :before :after inside the class spec:

<style type="text/css">
div.bibtexentry { margin-left: 2em; text-indent: -2em; }
span.bibtexlabel:before{ content: "["; }
span.bibtexlabel:after{ content: "] "; }
</style>

<span class='bibtexlabel'>1</span><span>entry</span>

However, when Calibre imports this, it seems to ignore the span class, as the entries are

<span>1</span><span>entry</span>

and so show as
numberentry
not really good looking.
Is there anything I can do so Calibre gets the correct formatting for these labels?
Yes, I can pre-process the XHTML, that is my last resort.
Any ideas ?

BTW, hello everyone, I'm new ;^)