<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8" />
<title></title>
<style type="text/css">
.box
{
height: 100px;
width: 450px;
margin: 20px;
padding: 20px;
border: solid 20px #c60;
background-color: #f0f0f0;
}
</style>
</head>
<body>
<div class="box">盒状模型结构</div>
</body>
</html>
在默认布局下，当元素包含内容后，width和height会自动调整为内容的高度和宽度。原文：http://blog.csdn.net/lindonglian/article/details/46489247