How do I do it manually?
Generating the EPUB from KCC and run kindlegen.exe through CMD?
I've done that and that is what gives me the "Info(cssparser):I10004: @rules other than @import, @charset and @font-face are not supported." error.
If I take the EPUB that I get from KCC and convert it to MOBI through Calibre it works, but I don't get the panel view etc in my kindle, it is treated like a book (can't zoom and such). I guess it's some option.
I'll try get my hands on another version of kindlegen and see if it makes any difference later today after work