区别不同浏览器的CSS hack写法:
区别IE6与FF: background:orange;*background:blue;
区别IE6与IE7: background:green !important;background:blue;
区别IE7与FF: background:orange; *background:green;
区别FF,IE7,IE6: background:orange;*background:green !important;*background:blue;
注:IE都能识别*;标准浏览