.clearfix{*zoom :; }    /*IE6/IE7*/

 .clearfix:after{

     display: block;

     content: "clear";

     height:;

     clear: both;

     overflow: hidden;

     visibility: hidden;

 }

 .box{

     width:500px;

     height:500px;

     background-color:#eee;

     font-size:;

     *font-size:200px;

     text-align:center;

 }

 .box img{

     vertical-align:middle;

 }

 .box:after{

     display:inline-block;

     width:;

     height:100%;

     content:"center";

     vertical-align:middle;

     overflow:hidden;

 }

 p:before

 {

     content:"pre-";

     background-color:yellow;

     font-weight:bold;

     color: red;

 }