<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>practice</titlie>
<style>
.box{width:400px; height:400px;background:#333; border:1px solid blue;}
.content{height:inherit; background:#f00;padding:20px;}
.content p { width:400px; height:40px; line-height:40px; font-size:14px; text-align:center; background:#333; color:#fff; margin-top:180px;}
</style>
</head>
<body>
<div class="box">
<div class="content">
<p>盒模型</p>
</div>
</div>
</body>
</html>
