window.onload=function(){
var men=document.getElementById('nav');
var menFixed=document.getElementById('Fixnav');
var abc=document.getElementById('abc');
window.onscroll=function(){
var scrollTop=document.documentElement.scrollTop||document.body.scrollTop;
if(scrollTop>men.offsetTop){
menFixed.style.display='block';
}else if(scrollTop
menFixed.style.display='none';
}
}
};
abc是内容里面最后一个盒子。求大神帮忙!