css Validations gives xml error

Dear Sirs,

I've been trying to validate the following document's css:
http://www.tomatoma.ws/index.html

It validates as an XHTML 1.0 Transitional and the css validates when on its
own but when triying to validate the html document for css well formedness
it gives the error stated below. In line 47 there's no element a whatsoever,
I've looked everywhere and can't find the error:

Target: http://www.tomatoma.ws/
Please, validate your XML document first!

Line 47

Column 5

The element type "a" must be terminated by the matching end-tag "".

¿Could you please give a hint about what's happening?

Yours sincerely

Isabel Hidalgo