For the record ... The current epub 3 spec is version "3.0.1" (not to be confused with the recently proposed epub 3.1 spec that really should have been called epub 4) that basically specifies CSS 3 with some extensions.
The full link to the relevant section regarding stylesheets is provided here:
http://www.idpf.org/epub/301/spec/ep...s.html#sec-css
As far as I know, no one implements the epub3 epub specific -epub extensions to CSS 3.