Differences in CSS behavior between Firefox and Google Chrome/Safari
are quite likely to be bugs, regardless at which level (end-user code,
implementation or specification). If you want to verify which browser
might be wrong, always test using the latest versions (nightlies, if
available) and compare the output to Opera (11) or Internet Explorer
(9).
Keep in mind that certain CSS properties may be prefixed, such as
"-moz-outline-radius" and "-webkit-box-reflect". In that case the
implementation is experimental and sometimes not even available in a
specification.
Regards,
Peter Beverloo