css hack兼容写法

    #test  
    {  
        width:300px;  
        height:300px;  
        color:red !important;/* Firefox、IE7支持 */
        background-color:blue;      /*firefox*/
        background-color:red\9;      /*all ie*/
        background-color:yellow\0;    /*ie8*/
        +background-color:pink;        /*ie7*/
        _background-color:orange;       /*ie6*/
    } 
    :root #test { background-color:purple\9; }  /*ie9*/
    @media all and (min-width:0px){ #test {background-color:black\0;} }  /*opera*/
    @media screen and (-webkit-min-device-pixel-ratio:0){ #test {background-color:gray;} }  /*chrome and safari*/
 body:nth-of-type(1) p{color:red;} /* Chrome、Safari支持 */