From my brief search via Google, all I could find is the CSS spec at w3.org which only states the nature of the keywords, ie. the fact that they exist and start with the @ character and where they must be located.
What I'm after though is a list of the actual valid keywords and what they mean. The only one I know and (hopefully) understand is @import. The w3.org pages also mention @page and @media but I'm not sure what exactly they are for.
Note that this is not needed for anything important. Just wanting to satisfy my curiosity.
Cheers.