<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<style>
#div1{
width: 300px;
height: 300px;
background-color: red;
position: relative;
}
#div2{
width: 200px;
height: 200px;
background-color: orange;
position: absolute;
left: 50%;
margin-left: -100px;
top: 50%;
margin-top: -100px;
}
</style>
<title>DIV居中</title>
</head>
<body>
<div id="div1">
<div id="div2">
</div>
</div>
</body>
</html>
