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 })