<!doctype html>
<html>
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
<title>现代浏览器博物馆</title>
</head>
<body>
<nav class="navbar navbar-default navbar-inverse" role="navigation">
<div class="container-fluid">
<div class="navbar-header">
<button type="button" class="navbar-toogle collapsed" date-toggle="collapse" data-target="#bs-example-navbar-collapse-1">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a class="navbar-brand" href="#">现代浏览器博物馆</a>
</div>
<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
<ul class="nav navbar-nav">
<li class="active"><a href="#">综述</a></li>
<li><a href="#">简述</a></li>
<li><a href="#">特点</a></li>
<li><a href="#">关于</a></li>
</ul>
</div>
</div>
</nav>
<!-- Optional JavaScript -->
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="http://cdn.bootcss.com/jquery/1.11.1/jquery.min.js"></script>
<script src="http://cdn.bootcss.com/bootstrap/3.2.0/js/bootstrap.min.js"></script>
</body>
</html>
dropdown等属性没有设置