Some CSS hack of IE6 IE7 IE8 FF

P {+ color: # f00;} supports IE6 IE7 and does not support FF IE8

P {_ color: # f00;} supports IE6 and does not support FF.

P {color: # 00f! Important ;}
P {color: # f00;} supports IE7 IE6 FF IE8

P {color: # 00f! Important; color: # f00;} supports IE7 IE8 FF and does not support IE6

Head: first-child + body p {color: # f00;} supports IE7 IE8 FF and does not support IE6

/*\*//*/
P {color: # f00 ;}
/**/Supports IE8 and does not support IE6 IE7 FF

Html * p {color: # f00;} supports IE6 IE7 and does not support FF IE8

Html> p {color: # f00;} supports IE7 IE8 FF and does not support IE6

Html [xmlns] p {color: # f00;} supports IE7 IE8 FF and does not support IE6

@ Import 'style.css ';
@ Import "style.css ";
@ Import url(style.css );
@ Import url('style.css ');
@ Import url ("style.css"); supports IE7 IE6 FF IE8

P {/*/color: # f00;/**/} supports IE6 IE7 FF and does not support IE8

* Html p {color: # f00;} supports IE6 and does not support FF IE7 IE8.

* + Html p {color: # f00;} supports IE7 IE8 and does not support FF IE6

P {* color: # f00;} supports IE7 IE6 and does not support FF IE8