我用的DW写的，为什么出不来效果
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>现代浏览器博物馆</title>
<link href="css/bootstrap.min.css" rel="stylesheet">
</head>
<body>
<nav class="navbar navbar-default navbar-fixed-top navbar-inverse">
<div>
<div>
<button type="button" data-toggle="collapse" class="navbar-toggle collapse" data-target="#bs-example-navbar-collapse-1"></button>
<span></span>
<span></span>
<span></span>
<span></span>
<a 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><a href="#">综述</a></li>
<li><a href="#">简述</a></li>
<li><a href="#">关于</a></li>
</ul>
</div>
</div>
</nav>
<script src="js/jquery-1.11.1.min.js"></script>
<script src="js/bootstrap.min.js"></script>
</body>
</html>
