<html>
<head>
<meta charset="utf-8">
<style>
.circle1,
.circle2,
.circle3,
.circle4,
.circle5{
position:absolute;
width:100px;
height:100px;
border:5px solid black;
border-radius:50%;
}
.circle1{
border-color:red;
left:0;
top:0;
}
.circle2{
border-color:green;
left:115px;
top:0;
z-index:5;
}
.circle3{
border-color:yellow;
left:230px;
top:0;
}
.circle4{
border-color:blue;
left:57px;
top:70px;
}
.circle5{
border-color:purple;
left:175px;
top:70px;
}
</style>
<title>五环</title>
</head>
<body>
<div class="main">
<div class="circle1"></div>
<div class="circle2"></div>
<div class="circle3"></div>
<div class="circle4"></div>
<div class="circle5"></div>
</div>
</body>
<html>