<!DOCTYPE html>
<html>
<head>
<style type='text/css'>
html, body {
height: 100%;
margin: 0;
padding: 0;
}
.header {
background: url(http://www.w3cschool.cn/style/download.png) no-repeat center center fixed;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
height: inherit;
}
</style>
</head>
<body>
<div class="header"></div>
<p>Content below header</p>
</body>
</html>