关于网站代码的问题,

<!-- CSS部分 ##### 请修改为自己的样式-->
<STYLE type=text/css>
.sec1 { cursor: hand;background:#CCCCCC;}
.sec2 { font-weight:: bold; cursor: hand;background:#FFFFFF;}
.layer {border:#CCCCCC 1px solid; width:400px;}
</STYLE>

<!--JavaScript部分-->
<SCRIPT language=javascript>
<!--
function secBoard(n)
{
for(i=0;i<secTable.cells.length;i++)
secTable.cells[i].className=sec1;
secTable.cells[n].className=sec2;
for(i=0;i<mainTable.tBodies.length;i++)
mainTable.tBodies[i].style.display=none;
mainTable.tBodies[n].style.display=block;
}
//-->
</SCRIPT>
<!--HTML部分-->
<div class=layer>
<TABLE id=secTable cellSpacing=0 cellPadding=0 width=400 height=25 border=0
>
<TR align=middle height=25>
<TD class=sec2 onclick=secBoard(0)> 推荐</TD>
<TD class=sec1 onclick=secBoard(1)> 电影</TD>
<TD class=sec1 onclick=secBoard(2)> 剧集</TD>
<TD class=sec1 onclick=secBoard(3)> 音乐</TD>
</TR>
</TABLE>
<TABLE id=mainTable width=400 border=0>
<TBODY style=DISPLAY: block>
<TR>
<TD>
<TABLE width=99% border=0>
<TBODY>
<TR>
<td valign=middle>推荐</td>
</TR>
</TBODY>
</TABLE>
</TD></TR></TBODY>
<TBODY style=DISPLAY: none>
<TR>
<TD>
<TABLE width=99% border=0>
<TBODY>
<TR>
<td valign=middle>电影</td>
</TR>
</TBODY>
</TABLE>
</TD></TR></TBODY>
<TBODY style=DISPLAY: none>
<TR>
<TD>
<TABLE width=99% border=0>
<TBODY>
<TR>
<td valign=middle>剧集</td>
</TR>
</TBODY>
</TABLE>
</TD></TR></TBODY>
<TBODY style=DISPLAY: none>
<TR>
<TD>
<table width=99% border=0>
<tbody>
<tr>
<td valign=middle>音乐</td>
</tr>
</tbody>
</table>
</TD>
</TR></TBODY></TABLE>
</div>