css样式图片居中显示，不平铺

css：

--------------------------------------

#box{
1000px;
height:500px;
border:1px solid #009;
background:url("ur;") no-repeat center center;
-webkit-background-size:contain;
background-size:contain;
}

#box{
1000px;
height:500px;
border:1px solid #009;
background:url("ur;") no-repeat center center;
-webkit-background-size:contain;/**--cover**/
background-size:contain;/**--cover**/
}

html：

--------------------------------------

  <div id="box" src=""></div>