CSS匣子模式 _HTML/CSS

CSS盒子模式
http://www.blueidea.com/articleimg/2007/03/4545/css2.html彻底弄懂CSS盒子模式(DIV布局快速入门)
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http://www.blueidea.com/articleimg/2007/03/4545/css1.html

<style type="text/css">
<!--
* {
margin: 0px;
padding: 0px;
}
body {
font-family: Arial, Helvetica, sans-serif;
font-size: 12px;
margin: 0px auto;
height: auto;
width: 760px;
border: 1px solid #006633;
}
#header {
height: 25px;
width: 740px;
background-image: url(headPic.gif);
background-repeat: no-repeat;
margin:0px 0px 3px 0px;
background-color:#006633
}
#nav {
height: 25px;
width: 740px;
font-size: 14px;
list-style-type: none;
}
#nav li {
float:left;
}
#nav li a{
color:#000000;
text-decoration:none;
padding-top:4px;
display:block;
width:97px;
height:22px;
text-align:center;
background-color: #009966;
margin-left:2px;
}
#nav li a:hover{
background-color:#006633;
color:#FFFFFF;
}
#content {
height:auto;
width: 740px;
line-height: 1.5em;
padding: 10px;
}
#content p {
text-indent: 2em;
}
#content h3 {
font-size: 16px;
margin: 10px;
}
#footer {
height: 50px;
width: 740px;
line-height: 2em;
text-align: center;
background-color: #006633;
padding: 10px;
}
-->
</style>
<body>
    <div id="header">
    <ul id="nav">
        <li><a href="#">首 页</a></li>
        <li><a href="#">文 章</a></li>
        <li><a href="#">相册</a></li>
        <li><a href="#">Blog</a></li>
        <li><a href="#">论 坛</a></li>
        <li><a href="#">帮助</a></li>
    </ul>
    </div>
    <div id="content">
        <h3>前言</h3>
        <p>第一段内容</p>
        <h3>理解CSS盒子模式</h3>
        <p>第二段内容</p>
    </div>
    <div id="footer">
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    </div>
</body>