JS实现顶部可关闭自适应浮动广告条

<html>
<head>
<title>网站页首可关闭广告条</title>
<style type="text/css">
<!--
body { margin: 0px;padding: 0px;text-align: center;}
TD {FONT-SIZE: 12px; COLOR: #333;}
#topadv {BORDER-BOTTOM: #e2e2e2 1px solid;}
-->
</style>
</head>
<body>
<SCRIPT>
 function floatadv(){
  document.getElementById("topadv").style.display="none";
 }
</SCRIPT>
<DIV id=topadv>
<table width="100%" border="0" cellspacing="0" cellpadding="0">
 <tr>
 <td width="4%" height="30" align="center"><img src="images/kids.gif" width="15" height="14"></td>
 <td width="82%"><a href="https://www.jb51.net/">本站</a>是国内专业的网站建设资源、脚本编程学习类网站，提供asp、php、asp.net、javascript、jquery、vbscript、dos批处理、网页制作、网络编程、网站建设等编程资料。</td>
 <td width="14%" align="right"><a style="CURSOR: hand" onClick=floatadv()><img 
 src="images/close.gif" width=84 height=11 hspace="6" border=0></a></td>
 </tr>
</table>
</DIV>
</body>
</html>