style-rule　::=　selectors-list　{　properties-list　}　...　其中　selectors-list　::=　selector[　:　pseudo-class]　[　::　pseudo-element]　[　,　selectors-list]　properties-list　::=　[property　:　value]　[　;　properties-list]　参阅后面的selector、　pseudo-element　、pseudo-class　列表。