本文作者html5tricks，转载请注明出处
Bootstrap是Twitter推出的一个用于前端开发的开源工具包，基于Bootstrap框架，我们可以方便地制作漂亮的UI界面。今天要分享的这款CSS3下拉菜单就是基于Bootstrap的，下拉子菜单的外观也非常不错，同时菜单也具有3D立体的视觉效果。
下面我们一起来看看实现这款CSS3 3D菜单的过程和源码，代码主要由HTML、CSS和jQuery组成。
HTML代码：
<nav class="navbar navbar-inverse" role="navigation"><div class="container-fluid">
<!-- 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="#">Link</a></li>
<li><a href="#">Link</a></li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown <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>
</ul>
<ul class="nav navbar-nav navbar-right">
<li><a href="#">Link</a></li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown <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>
</ul>
</li>
</ul>
</div><!-- /.navbar-collapse -->
</div><!-- /.container-fluid -->
</nav>
菜单格式也使用了传统的ul li层级列表，主要是利用CSS3来美化。
CSS代码：
引用Bootstrap的CSS样式：
<link rel="stylesheet" href="http://netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css"> <link rel="stylesheet" href="http://netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap-theme.min.css">
.body-wrap{min-height:700px; }
.body-wrap {
position: relative;
z-index: 0;
background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAoAAAAKCAYAAACNMs+9AAAASUlEQVQYV2PcsWOHpIeHx3MGJIAuBuIzIivApxiukJDJYIXYFKHbxIjNPSBF6O7GcCNII7pCvJ6BWQ2zkTTPoOvGFmRYPYMtAgCh0ELO5eiG4gAAAABJRU5ErkJggg==);
}
.body-wrap:before,
.body-wrap:after {
content: '';
position: absolute;
top: 0;
left: 0;
right: 0;
z-index: -1;
height: 260px;
background: url(data:image/svg+xml;base64,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);
background: -moz-linear-gradient(top, rgba(26,49,95,1) 0%, rgba(26,49,95,0) 100%);
background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(26,49,95,1)), color-stop(100%,rgba(26,49,95,0)));
background: -webkit-linear-gradient(top, rgba(26,49,95,1) 0%,rgba(26,49,95,0) 100%);
background: -o-linear-gradient(top, rgba(26,49,95,1) 0%,rgba(26,49,95,0) 100%);
background: -ms-linear-gradient(top, rgba(26,49,95,1) 0%,rgba(26,49,95,0) 100%);
background: linear-gradient(to bottom, rgba(26,49,95,1) 0%,rgba(26,49,95,0) 100%);
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#1a315f', endColorstr='#001a315f',GradientType=0 );
}
.body-wrap:after {
top: auto;
bottom: 0;
background: url(data:image/svg+xml;base64,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);
background: -moz-linear-gradient(top, rgba(26,49,95,0) 0%, rgba(26,49,95,1) 100%);
background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,rgba(26,49,95,0)), color-stop(100%,rgba(26,49,95,1)));
background: -webkit-linear-gradient(top, rgba(26,49,95,0) 0%,rgba(26,49,95,1) 100%);
background: -o-linear-gradient(top, rgba(26,49,95,0) 0%,rgba(26,49,95,1) 100%);
background: -ms-linear-gradient(top, rgba(26,49,95,0) 0%,rgba(26,49,95,1) 100%);
background: linear-gradient(to bottom, rgba(26,49,95,0) 0%,rgba(26,49,95,1) 100%);
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#001a315f', endColorstr='#1a315f',GradientType=0 );
}
nav{margin-top:60px;box-shadow: 5px 4px 5px #000;
}
jQuery代码：
$('ul.nav li.dropdown').hover(function() {
$(this).find('.dropdown-menu').stop(true, true).delay(200).fadeIn(500);
}, function() {
$(this).find('.dropdown-menu').stop(true, true).delay(200).fadeOut(500);
});
