nav置顶和footer置低

清华大佬耗费三个月吐血整理的几百G的资源,免费分享!....>>>

 nav{ 
height:50px; 
width:100%;
position:fixed;
background:#9b95c9;
top:0; 
left:0; 
right:0;
z-index:999; 
}
footer{
width:100%;
height:30px;
background:#aaa;
left:0;
right:0;
bottom:0;
position:fixed;
}