我正在从courcera学习html、css和bootstrap课程，讲师已经提供了他所做的每个项目的代码。当我复制这段代码来测试它时，我正在听讲座。菜单按钮似乎为他下拉，但不为我下拉。我是新的 为什么菜单按钮不起作用？
body {
font-size: 16px;
color: #fff;
background-color: #61122f;
font-family: 'Oxygen', sans-serif;
}
/** HEADER **/
#header-nav {
background-color: #f6b319;
border-radius: 0;
border: 0;
}
#logo-img {
background: url('../images/restaurant-logo_large.png') no-repeat;
width: 150px;
height: 150px;
margin: 10px 15px 10px 0;
}
.navbar-brand {
padding-top: 25px;
}
.navbar-brand h1 {
/* Restaurant name */
font-family: 'Lora', serif;
color: #557c3e;
font-size: 1.5em;
text-transform: uppercase;
font-weight: bold;
text-shadow: 1px 1px 1px #222;
margin-top: 0;
margin-bottom: 0;
line-height: .75;
}
.navbar-brand a:hover,
.navbar-brand a:focus {
text-decoration: none;
}
.navbar-brand p {
/* Kosher cert */
color: #000;
text-transform: uppercase;
font-size: .7em;
margin-top: 15px;
}
.navbar-brand p span {
/* Star-K */
vertical-align: middle;
}
#nav-list {
margin-top: 10px;
}
#nav-list a {
color: #951C49;
text-align: center;
}
#nav-list a:hover {
background: #E7E7E7;
}
#nav-list a span {
font-size: 1.8em;
}
#phone {
margin-top: 5px;
}
#phone a {
/* Phone number */
text-align: right;
padding-bottom: 0;
}
#phone div {
/* We Deliver */
color: #557c3e;
text-align: right;
padding-right: 15px;
}
.navbar-header button.navbar-toggle,
.navbar-header .icon-bar {
border: 1px solid #61122f;
}
.navbar-header button.navbar-toggle {
clear: both;
margin-top: -30px;
}
/* END HEADER */<!doctype html>
<html lang="en">
<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>David Chu's China Bistro</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<link rel="stylesheet" href="styles.css">
<link href='https://fonts.googleapis.com/css?family=Oxygen:400,300,700' rel='stylesheet' type='text/css'>
<link href='https://fonts.googleapis.com/css?family=Lora' rel='stylesheet' type='text/css'>
</head>
<body>
<header>
<nav id="header-nav" class="navbar navbar-default">
<div class="container">
<div class="navbar-header">
<a href="index.html" class="pull-left visible-md visible-lg">
<div id="logo-img"></div>
</a>
<div class="navbar-brand">
<a href="index.html">
<h1>David Chu's China Bistro</h1>
</a>
<p>
<img src="images/star-k-logo.png" alt="Kosher certification">
<span>Kosher Certified</span>
</p>
</div>
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#collapsable-nav" aria-expanded="false">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
</div>
<div id="collapsable-nav" class="collapse navbar-collapse">
<ul id="nav-list" class="nav navbar-nav navbar-right">
<li>
<a href="menu-categories.html">
<span class="glyphicon glyphicon-cutlery"></span><br class="hidden-xs"> Menu</a>
</li>
<li>
<a href="#">
<span class="glyphicon glyphicon-info-sign"></span><br class="hidden-xs"> About</a>
</li>
<li>
<a href="#">
<span class="glyphicon glyphicon-certificate"></span><br class="hidden-xs"> Awards</a>
</li>
<li id="phone" class="hidden-xs">
<a href="tel:410-602-5008">
<span>410-602-5008</span></a>
<div>* We Deliver</div>
</li>
</ul>
<!-- #nav-list -->
</div>
<!-- .collapse .navbar-collapse -->
</div>
<!-- .container -->
</nav>
<!-- #header-nav -->
</header>
<div id="call-btn" class="visible-xs">
<a class="btn" href="tel:410-602-5008">
<span class="glyphicon glyphicon-earphone"></span> 410-602-5008
</a>
</div>
<div id="xs-deliver" class="text-center visible-xs">* We Deliver</div>
<!-- jQuery (Bootstrap JS plugins depend on it) -->
<script src="js/jquery-2.1.4.min.js"></script>
<script src="js/bootstrap.min.js"></script>
<script src="js/script.js"></script>
</body>
</html>使用弹出窗口，我不知道，但我认为新功能弹出窗口更好 并将其设置为：
popover=""popoverTarget="write an id of that element"