1)absolute与height:100%
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="initial-scale=1.0, maximum-scale=1.0, user-scalable=no" />
<title></title>
<style>
html{height: 100%;}
body{padding:0px;margin:0px;overflow: hidden;height: 100%;}
header{height: 50px;line-height: 50px;background: red;text-align: center;}
section{height: 100%;overflow-y: auto;}
.content{padding-bottom: 100px;}
footer{height: 50px;line-height: 50px;background: red;position: absolute; 100%;bottom: 0px;text-align: center;}
</style>
</head>
<body>
<header>我是头部</header>
<section>
<div class="content"></div>
</section>
<footer>我是底部</footer>
</body>
</html>
2) flex与 height: 100vh
<!DOCTYPE html>