特点
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
*{
padding: 0;
margin: 0
}
.box1{
width: 200px;
height: 200px;
background-color: red;
position:relative;
top: 30px;
left: 40px;
z-index: 3;
}
.box2{
width: 200px;
height: 200px;
background-color: yellow;
position: relative;
top: 0;
left: 0;
z-index: 2;
}
.box3{
width: 200px;
height: 200px;
background-color: green;
float: left;
margin-left: 20px;
margin-top: -30px;
}
</style>
</head>
<body>
<div class="box1"></div>
<div class="box2"></div>
<div class="box3"></div>
</body>
