jquery导航条悬浮停止(浏览器窗口)页面顶部 兼容ie6

.nav_scroll{ position:fixed;top:0;left:0;z-index:1200; width:100%;}

<script type="text/javascript">
$(function(){

if ($.browser.msie && ($.browser.version == "6.0") && !$.support.style) {
var handler,sTop,dTop;
    dTop = $("#fixedNav").offset().top
    $(window).bind('scroll',function(){
        window.clearTimeout(handler);
        handler = window.setTimeout(function(){
            sTop = $(document).scrollTop();
            sTop > dTop ? $("#fixedNav").css("top",sTop - dTop) : $("#fixedNav").css("top",0);
     $("#fixedNav").css({"position":"relative","z-index":"1200"});
        },60);
    });
}else{

 var topMain= $("#fixedNav").offset().top
 $(window).scroll(function(){
  if ($(window).scrollTop()>topMain){
   $("#fixedNav").addClass("nav_scroll");
  }else{
   $("#fixedNav").removeClass("nav_scroll");
  }
 });

 }
});
</script>

<div id=fixedNav>

<div class="mainMenu">
 <div class="greenMenu">
     <span class="greena">
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        </span>   
   </div>
</div>