1、一个宽高200px的div在浏览器中居中
div{
width:200px;
height:200px;
position:absolute;
top:50%;
left:50%;
margin-left:-100px;
margin-top:-100px;
}
div{
width:200px;
height:200px;
position:absolute;
top:50%;
left:50%;
margin-left:-100px;
margin-top:-100px;
}