分享一段代码示例，它实现了简单的下拉菜单效果。
但是下拉菜单具有3D旋转效果，代码实例如下:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="author" content="http://www.softwhy.com/" />
<title>学习扣群：767273102 </title>
<meta name="keywords" content="" />
<style type="text/css">
*{margin:0 auto;}
body{
background-color: #EEEEEE;
font-family: Microsoft Yahei,Arial,sans-serif;
}
nav{
width:100%;
background-color:#455552;
position:relative;
width:650px;
margin-top:100px;
}
.nav-ul{
list-style:none;
}
.nav-ul>li{
display:inline-block;
position:relative;
}
.nav-ul a{
text-decoration:none;
color:#FFF;
display:inline-block;
padding:10px 20px;
}
.nav-ul a:hover{
background-color: #1ABC9C;
}
.nav-ul a:hover+ul li{
opacity:1;
-webkit-transform: rotateY(0deg);
transform: rotateY(0deg);
}
.nav-ul a+ul{
list-style: none;
position: absolute;
transition: opacity 0.5s;
-webkit-perspective:800;
-webkit-transform-style: preserve-3d;
}
.nav-ul a+ul:hover li{
opacity: 1;
-webkit-transform: rotateY(0deg);
transform: rotateY(0deg);
}
.nav-ul a+ul li{
position: relative;
left: -40px;
opacity: 0;
width: 150px;
transition: transform 1.5s,opacity 0.8s;
}
.nav-ul a+ul a{
display: inline-block;
width: 75%;
background-color: rgba(26,188, 156, 0.75);
}
.nav-effect-1{
transform: rotateY(90deg) translateX(10px);
}
.nav-effect-2{
transform: rotateY(120deg) translateX(20px);
}
.nav-effect-3{
transform: rotateY(150deg) translateX(30px);
}
.nav-effect-4{
transform: rotateY(180deg) translateX(40px);
}
.nav-ul a+ul a:hover{
background-color: rgba(69,85, 82, 0.75);
}
</style>
</head>
<body>
<nav>
<ul class="nav-ul">
<li><a href="/">首页</a></li>
<li>
<a href="#">web前端开发</a>
<ul>
<li class="nav-effect-1"><a href="#">JavaScript</a></li>
<li class="nav-effect-2"><a href="#">JQuery</a></li>
<li class="nav-effect-3"><a href="#">CSS</a></li>
<li class="nav-effect-4"><a href="#">HTML</a></li>
</ul>
</li>
<li>
<a href="#">后端</a>
<ul>
<li class="nav-effect-1"><a href="#">Python</a></li>
<li class="nav-effect-2"><a href="#">PHP</a></li>
</ul>
</li>
<li>
<a href="#">琐碎杂类</a>
<ul>
<li class="nav-effect-1"><a href="#">softwhy.com</a></li>
<li class="nav-effect-2"><a href="#">Ajax</a></li>
</ul>
</li>
<li>
<a href="#">我的生活</a>
<ul>
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<li class="nav-effect-2"><a href="#">Review</a></li>
<li class="nav-effect-3"><a href="#">Sentiment</a></li>
</ul>
</li>
<li>
<a href="#">关于我</a>
<ul>
<li class="nav-effect-1"><a href="/contribute">web前端开发学习q群：767273102 技术分享，欢迎基础小伙伴</a></li>
<li class="nav-effect-2"><a href="/message">留言板</a></li>
</ul>
</li>
</ul>
</nav>
</body>
</html>