CSS IE6 IE7 ff CSS hack use tips _ Experience Exchange

FF Browser
. test{
height:20px;
Background-color:orange;
}
IE7 Browser
*+html. test{/*ie7*/
height:20px;
Background-color:blue;
}

IE6 Browser

*html. test{/*ie6*/
height:20px;
Background-color:black;
}

The above CSS code shows that FF is still the most obedient browser. In IE6 and IE7 if you want to use hack you must precede with the tag HTML.
Here is a good memory, IE6 plus *html, and IE7 plus *+html, hint added a version.
The advantage of CSS hack by class, ID is that it does not have to take into account the sequence, and is easy for management and other people to accept, but also through this hack similar to the JS browser version of the control.