<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>
<style>
.front{ background-repeat:repeat-x !important;}<!--important 优先级最高，（可以防止被其他样式覆盖）-->
.back{ width:800px; height:6000px; border:1px solid #F00; background-image:url(png.png) ; background-position:-100px -100px; background-repeat:no-repeat;}
/*.back{ width:800px; height:600px; background:url(png.png) no-repeat left top ; border:1px solid #F00}*/
</style>
<body>
<div class="back front">
</div>
</body>
</html>
