1.让footerr固定在底部
来源于http://ryanfait.com/resources/footer-stick-to-bottom-of-page/一种很简单的方法：
<body>
<div class="wrapper">
<p>Your website content here.</p>
<div class="push"></div>
</div>
<div class="footer">
<p>Copyright (c) 2008</p>
</div>
</body>
<style>
* {
margin: 0;
}
html, body {
height: 100%;
}
.wrapper {
min-height: 100%;
height: auto !important;
height: 100%;
margin: 0 auto -4em;
}
.footer, .push {
height: 4em;
}
.footer{
background: #400;
}
</style>