设置div中的div居中显示
方法一、
<div class='big'>
<div class='small'>box1</div>
</div>
style样式：
.big{
height:200px;
width:200px;
border:black solid 1px;
position:absolute;
left:150px;
}
.small{
height:100px;
width:100px;
background-color:green;
position:relative;
left:100px;
top:100px;
margin-top:-50px;
margin-left:-50px;
border:black solid 1px;
}
方法二、
div class='big2'>
<div class='small2'>box3</div>
</div>
.big2{
height:200px;
width:200px;
border:black solid 1px;
text-align:center;
}
.small2{
height:100px;
width:100px;
background-color:green;
margin:50px auto; //外面的div高度的一半
border:black solid 1px;
}