一、css实现
1、margin
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<style>
*{
margin: 0;
padding: 0;
}
.div1{
height: 500px;
background: #ff0000;
overflow: hidden;/*解决外边距合并*/
}
.div2{
width: 200px;
height: 200px;
background: #ffff00;
margin:150px auto;/*设置宽才有用*/
}
</style>
</head>
<body>
<div class="div1">
<div class="div2"></div>
</div>
</body>
</html><!DOCTYPE html>
<html lang
