让背景图片一直不动

<style>


body {
background-image: url(http://www.baidu.com/img/baidu_sylogo1.gif);
background-repeat: no-repeat;
font-family: "宋体";
font-size: 12px;
line-height: normal;
font-weight: normal;
color: #000;
background-attachment: fixed;
}

</style>