ie6 css dispaly block 不显示


<style>
   .alink{ display:block; width:100px; height:25px; background:#FF0000; text-decoration:none; color:#FFF; }
     .curr{ display:block; width:70px; height:100%;   font-size:14px;  font-color:#E8f8f8; background:url(images/bj1.jpg) no-repeat;text-decoration:none;   }
    </style><script language="javascript" type="text/javascript">    window.onload=function(){
    var lk1=document.getElementById('lk1');
    lk2=document.getElementById('lk2');
    lk3=document.getElementById('lk3');
    if(location.href.toString().indexOf('0728')>-1)
    {lk1.className="curr"
    }
    else if(location.href.toString().indexOf('about')>-1)
    {lk2.className="curr"
    }
    else if(location.href.toString().indexOf('newslist')>-1)
    {lk3.className="curr"
    }
</script><ul  style=" text-align:center"   class="Navigate">
            <li> <A class=td1   id="lk1"
          href="Default0728.aspx">首页</A> </li>
                <li>  <A class=td1  id="lk2" 
          href="about.aspx">走进源峰</A> </li>
                <li> <A class=td1   id="lk3"
          href="newslist.aspx">新闻中心</A> </li>
</ul>