<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>固定导航栏</title>
<style type="text/css">
* {
margin: 0;
padding: 0;
}
.main {
width: 1000px;
margin: 0 auto;
}
/*.top {
height: 171px;
}
.nav {
height: 86px;
}*/
</style>
<script src="jquery-1.12.2.js"></script>
<script>
$(function () {
$(window).scroll(function () {
//获取页面卷曲出去的高度和.top的div的高度对比
if($(document).scrollTop()>$(".top").height()){
$(".nav").css({"position":"fixed","top":0});
$(".main").css("marginTop",$(".nav").height());
}else{
$(".nav").css("position","static");
$(".main").css("marginTop",0);
}
});
});
</script>
</head>
<body>
<div class="top">
<img src="images/top.png" />
</div>
<div class="nav">
<img src="images/nav.png" />
</div>
<div class="main">
<img src="images/main.png" />
</div>
</body>
</html> 