Css的background的详细介绍
    <!DOCTYPE html>
<html>
  <head>
    <title>CSS01.html</title>	
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
	<style type="text/css">
		*{
			margin: 0px;
			padding: 0px;
		}
		div{
			width: 800px;
			height:600px;
			background-color: yellow;
		}
		#d1{
			background-image: url(../pic/a.jpg);
			background-repeat: no-repeat;/*不重复,就是不铺满啊*/
			background-attachment:fixed;/*让图片固定,不要随着滚动条的滚动而出现图片的上下移动*/
		}
	</style>
</head>
  <body>
  	测试
    <div id="d1"></div>
  </body>
  <script type="text/javascript">
  	document.getElementById('d1').style['backgroundAttachment'] = 'scroll ';
  	document.getElementById('d1').style.backgroundImage = 'url(../pic/a.jpg)';
  	function $(id){return document.getElementById(id);}
  	$('d1').style.backgroundRepeat = 'no-repeat';
</script>
</html>