这是一款基于bootsnav的简洁多级导航菜单。bootsnav是以bootstrap为基础的导航菜单插件。被多级导航菜单效果是在bootsnav的基础上，对菜单样式进行了一些美化加工。

使用方法

在页面中引入bootstrap相关文件，jquery和bootsnav相关文件。

<link href="path/to/bootstrap.min.css" rel="stylesheet">
<link href="path/to/font-awesome.min.css" rel="stylesheet">
<link rel="stylesheet" type="text/css" href="css/bootsnav.css">
<script type="text/javascript" src="path/to/jquery.min.js"></script>
<script src="path/to/bootstrap.min.js"></script>
<script type="text/javascript" src="path/to/bootsnav.js"></script>
HTML结构

该多级导航菜单的基本HTML结构如下：

<div class="container">
    <div class="row">
        <div class="col-md-12">
            <nav class="navbar navbar-default navbar-mobile bootsnav on">
                <div class="navbar-header">
                    <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#navbar-menu">
                        <i class="fa fa-bars"></i>
                    </button>
                </div>
                <div class="collapse navbar-collapse" id="navbar-menu">
                    <ul class="nav navbar-nav" data-in="fadeInDown" data-out="fadeOutUp">
                        <li><a href="#">Home</a></li>
                        <li><a href="#">About Us</a></li>
                        <li class="dropdown">
                            <a href="#" class="dropdown-toggle" data-toggle="dropdown">Shortcodes</a>
                            <ul class="dropdown-menu animated">
                                <li><a href="#">Custom Menu</a></li>
                                <li><a href="#">Custom Menu</a></li>
                                <li class="dropdown">
                                    <a href="#" class="dropdown-toggle" data-toggle="dropdown">Sub Menu</a>
                                    <ul class="dropdown-menu animated">
                                        <li><a href="#">Custom Menu</a></li>
                                        <li><a href="#">Custom Menu</a></li>
                                        <li class="dropdown">
                                            <a href="#" class="dropdown-toggle" data-toggle="dropdown">Sub Menu</a>
                                            <ul class="dropdown-menu multi-dropdown animated">
                                                <li><a href="#">Custom Menu</a></li>
                                                <li><a href="#">Custom Menu</a></li>
                                                <li><a href="#">Custom Menu</a></li>
                                                <li><a href="#">Custom Menu</a></li>
                                            </ul>
                                        </li>
                                        <li><a href="#">Custom Menu</a></li>
                                    </ul>
                                </li>
                                <li><a href="#">Custom Menu</a></li>
                                <li><a href="#">Custom Menu</a></li>
                                <li><a href="#">Custom Menu</a></li>
                                <li><a href="#">Custom Menu</a></li>
                            </ul>
                        </li>
                        <li class="dropdown">
                            <a href="#" class="dropdown-toggle" data-toggle="dropdown">Pages</a>
                            <ul class="dropdown-menu animated">
                                <li><a href="#">Custom Menu</a></li>
                                <li><a href="#">Custom Menu</a></li>
                                <li class="dropdown">
                                    <a href="#" class="dropdown-toggle" data-toggle="dropdown">Sub Menu</a>
                                    <ul class="dropdown-menu animated">
                                        <li><a href="#">Custom Menu</a></li>
                                        <li><a href="#">Custom Menu</a></li>
                                        <li class="dropdown">
                                            <a href="#" class="dropdown-toggle" data-toggle="dropdown">Sub Menu</a>
                                            <ul class="dropdown-menu multi-dropdown animated">
                                                <li><a href="#">Custom Menu</a></li>
                                                <li><a href="#">Custom Menu</a></li>
                                                <li><a href="#">Custom Menu</a></li>
                                                <li><a href="#">Custom Menu</a></li>
                                            </ul>
                                        </li>
                                        <li><a href="#">Custom Menu</a></li>
                                    </ul>
                                </li>
                                <li><a href="#">Custom Menu</a></li>
                                <li><a href="#">Custom Menu</a></li>
                                <li><a href="#">Custom Menu</a></li>
                                <li><a href="#">Custom Menu</a></li>
                            </ul>
                        </li>
                        <li><a href="#">Portfolio</a></li>
                        <li><a href="#">Contact Us</a></li>
                    </ul>
                </div>
            </nav>
        </div>
    </div>
</div>
CSS样式

使用下面的CSS代码来对多级导航菜单进行美化。

.navbar-brand{
    padding: 29px 15px;
    height: auto;
}
nav.navbar.bootsnav{
    border: none;
    margin-bottom: 150px;
}
.navbar-nav{
    float: left;
}
nav.navbar.bootsnav ul.nav > li > a{
    color: #474747;
    text-transform: uppercase;
    padding: 30px;
}
nav.navbar.bootsnav ul.nav > li:hover{
    background: #f4f4f4;
}
.nav > li:after{
    content: "";
    width: 0;
    height: 5px;
    background: #34c9dd;
    position: absolute;
    bottom: 0;
    left: 0;
    transition: all 0.5s ease 0s;
}
.nav > li:hover:after{
    width: 100%;
}
nav.navbar.bootsnav ul.nav > li.dropdown > a.dropdown-toggle:after{
    content: "+";
    font-family: 'FontAwesome';
    font-size: 16px;
    font-weight: 500;
    position: absolute;
    top: 35%;
    right: 10%;
    transition: all 0.4s ease 0s;
}
nav.navbar.bootsnav ul.nav > li.dropdown.on > a.dropdown-toggle:after{
    content: "\f105";
    transform: rotate(90deg);
}
.dropdown-menu.multi-dropdown{
    position: absolute;
    left: -100% !important;
}
nav.navbar.bootsnav li.dropdown ul.dropdown-menu{
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.3);
    border: none;
}
@media only screen and (max-width:990px){
    nav.navbar.bootsnav ul.nav > li.dropdown > a.dropdown-toggle:after,
    nav.navbar.bootsnav ul.nav > li.dropdown.on > a.dropdown-toggle:after{ content: " "; }
    .dropdown-menu.multi-dropdown{ left: 0 !important; }
    nav.navbar.bootsnav ul.nav > li:hover{ background: transparent; }
    nav.navbar.bootsnav ul.nav > li > a{ margin: 0; }
}