Хаки для firefox 2 и firefox 1

Firefox 2
#id {/*normal style*/}
#id, x:-moz-any-link {/*for FF 2*/}
#id, x:-moz-any-link, x:default {/*reset styles for FF3 and later*/}

Firefox 1
#id, x:-moz-any-link {styles for Firefox 1.0 here}
#id, x:-moz-any-link, x:only-child {restore normal styles for newer versions}