<html lang="en">
<head>
<meta charset="utf-8">
<title>居中五环</title>
<link rel="stylesheet" type="text/css" href="lession6.css">
<head>
<body>
<div class="plat">
<div class="circle1"></div>
<div class="circle2"></div>
<div class="circle3"></div>
<div class="circle4"></div>
<div class="circle5"></div>
</div>
</body>
</html>
@charset "utf-8";
/* CSS Document */
*
{
margin:0;
padding:0;
}
.circle1,
.circle2,
.circle3,
.circle4,
.circle5{
position:absolute;
width:100px;
height:100px;
border:10px solid black;
border-radius:50%;
}
/*父级居中，子级也会跟着居中（父级作为一个操作平台） */
.plat{
position:relative;
top:50%;
left:50%;
margin-left:-190px;
margin-top:-93px;
/*border:5px solid black;*/
height:186px;
width:380px;s
}
.circle1{
border-color:red;
left:0;
top:0;
}
.circle2{
border-color:green;
left:130px;
top:0;
z-index:3; /*z-index属性设置元素的堆叠顺序，其值越高则在离我们观看者最近*/
}
.circle3{
border-color:yellow;
left:260px;
top:0;
z-index:4;
}
.circle4{
border-color:blue;
left:65px;
top:70px;
z-index:5;
}
.circle5{
border-color:purple;
left:195px;
top:70px;
z-index:6;
}