<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<!------ Include the above in your HEAD tag ---------->
<section>
<div class="menu_bar">
<div class="container">
<div class="row">
<nav class="navbar navbar-default" role="navigation">
<!-- Brand and toggle get grouped for better mobile display -->
<div class="navbar-header">
<button type="button" class="navbar-toggle" data-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="#">Brand</a>
</div>
<!-- Collect the nav links, forms, and other content for toggling -->
<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
<ul class="nav navbar-nav">
<li class="active"><a href="#">Home</a></li>
<li><a href="#">About</a></li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown">Service <b class="caret"></b></a>
<ul class="dropdown-menu">
<li><a href="#">Action</a></li>
<li><a href="#">Another action</a></li>
<li><a href="#">Something else here</a></li>
<li class="divider"></li>
<li><a href="#">Separated link</a></li>
<li class="divider"></li>
<li><a href="#">One more separated link</a></li>
</ul>
</li>
<li><a href="#">Disclaimer</a></li>
<li><a href="#">Blog</a></li>
<li><a href="#">Contact us</a></li>
</ul>
</div><!-- /.navbar-collapse -->
</nav>
</div>
</div>
</div>
</section>
.caret-up {
width: 0;
height: 0;
border-left: 4px solid rgba(0, 0, 0, 0);
border-right: 4px solid rgba(0, 0, 0, 0);
border-bottom: 4px solid;
display: inline-block;
margin-left: 2px;
vertical-align: middle;
}
.navbar-nav > li > a {
line-height: 50px;
padding-bottom: 20px;
padding-top: 20px;
}
$(function(){
$(".dropdown").hover(
function() {
$('.dropdown-menu', this).stop( true, true ).fadeIn("fast");
$(this).toggleClass('open');
$('b', this).toggleClass("caret caret-up");
},
function() {
$('.dropdown-menu', this).stop( true, true ).fadeOut("fast");
$(this).toggleClass('open');
$('b', this).toggleClass("caret caret-up");
});
});