1 <div class="cont">
2 <div id="top"> </div>
3 <div id="nav" class="nav"> </div>
4 </div>
5 <div style="height:1000px;"></div>
1 #top{width:100%;height:50px;border:1px solid red;}
2 .nav{width:1080px;height:50px;background:green;margin:0px auto;}
3 .scoll_nav{width:100%;position:fixed; top:10px; z-index:10000;}
1 $(document).ready(function(e) {
2 $(window).scroll(function() {
3 if($(window).scrollTop() > $("#top").height()+10){
4 $("#nav").addClass("scoll_nav")
5 }
6 else{
7 $("#nav").removeClass( "scoll_nav")
8 }
9 });
10 })
