css3中做3D导航栏

看别人做的一个3D导航栏，觉得很厉害，这里先保存下来，后面有时间好好分析一下：

<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>制作3D旋转导航</title>
    <style>
        @import url("http://www.w3cplus.com/demo/css3/base.css");
        /*任务一：引入本地字体文件*/
        @font-face{
            font-family:"fontt";
            src: url("http://www.imooc.com/Amaranth-BoldItalic.otf");
        }
        body {
            background-color:#edecec;
        }

        /* basic menu styles */
        .nav-menu {
            display: block;
            width:950px;
            margin: 50px auto 150px;
        }
        .nav-menu > li {
            display:inline;
            float:left;
            border-right:1px solid #edecec;
        }
        .nav-menu > li:last-child {
            border-right: none;
        }
        .nav-menu li a {
            color: #fff;
            display: block;
            text-decoration: none;
            /*调用本地字体*/
            font-family:fontt;
            -webkit-font-smoothing: antialiased;
            -moz-font-smoothing: antialiased;
            font-smoothing: antialiased;
            text-transform: capitalize;
            overflow: visible;
            line-height: 20px;
            font-size: 20px;
            padding: 15px 30px 15px 31px;
        }


        .three-d {
            /* 任务三、设置3D舞台布景 */
            perspective:200px;
            /*任务三  设置a元素.three-d为距离200px的3D舞台
            perspective理论是用户通过屏幕看到3D元素的距离，以像素px为单位
            */

            /*任务四、设置3D舞台布景过渡效果*/
            transition:all 0.3s linear;
            /*这里没有发现实际作用，望指出*/
            position: relative;
        }

        .three-d:not(.active):hover {
            cursor: pointer;
        }

        /*任务五、给不是当前状态的3D舞台的悬浮与聚焦状态设置变形效果*/
        .three-d:not(.active):hover .three-d-box,
        .three-d:not(.active):focus .three-d-box {
            transform:translateZ(-25px) rotateX(90deg);
            /*
            translateZ改变3D元素的Z轴高度，以用户看屏幕为准
            X是左右，Y是上下，Z可以理解为自身的深度,对于用户就是前后(屏幕距离)
            如果3D元素X轴旋转90度后，Z轴以用户看屏幕就变成了上下,
            X轴依旧是左右,Y轴变成了前后(屏幕距离)。
            这里没图说不清楚，看个人理解吧
            这里再次设置translateZ(-25px)是因为获取焦点后
            不会保留原本的translateZ数值


            rotateX改变3D元素的X轴角度,比如把这个元素横着插一根牙签，然后旋转
            (怎么转自己想，难道还能左右转)
            */
        }

        .three-d-box {
            /*任务六、给3D舞台中“.three-d-box”设置过渡与变形效果*/
            transition:all 0.3s linear;
            transform:translateZ(-25px);
            /*这里先设置translateZ(-25px)是为了子元素旋转效果需求，
            不然会造成拉近屏幕(深度)25px
            */
            -webkit-transform-style: preserve-3d;
            -moz-transform-style: preserve-3d;
            -ms-transform-style: preserve-3d;
            -o-transform-style: preserve-3d;
            transform-style: preserve-3d;
            /*规定如何在3D空间呈现子元素,(是否3D视图)*/
            -webkit-pointer-events: none;
            -moz-pointer-events: none;
            -ms-pointer-events: none;
            -o-pointer-events: none;

            pointer-events: none;
            /*pointer-events设置元素对于鼠标事件的限制*/
            position: absolute;
            top: 0;
            left: 0;
            display: block;
            width: 100%;
            height: 100%;
        }

        /*任务七、给导航设置3D前，与3D后变形效果*/
        .front {/*这个是未获取焦点时显示的那一面(正面)*/
            transform:rotateX(0deg) translateZ(25px);
            /*设置正面X轴不旋转(默认不转可以不设置)
            translateZ(25px)拉近正面深度距离，目的是不与背面重合
            */
        }

        .back {/*这个是获取焦点旋转后的那一面(底下货值背面)*/
            transform:rotateX(-90deg) translateZ(25px);
            /*设置背面X轴旋转-90度，
            translateZ(25px)因为已经旋转了，所以Z轴变成了上下，
            因为旋转的是-90 ， 反向，所以Z轴25px是向下，
            设置Z轴是为了和正面的底边接触，而不是正面的中点(一横)
            */
            color: #FFE7C4;
        }

        .front, .back {
            display: block;
            width: 100%;
            height: 100%;
            position: absolute;
            top: 0;
            left: 0;
            background: #74adaa;
            padding: 15px 30px 15px 31px;
            color: white;
            -webkit-pointer-events: none;
            -moz-pointer-events: none;
            -ms-pointer-events: none;
            -o-pointer-events: none;
            pointer-events: none;
            -webkit-box-sizing: border-box;
            box-sizing: border-box;
        }
        /*任务八、设置导航当前状态与悬浮状态下的背景效果*/
        .nav-menu li .active .front,
        .nav-menu li .active .back,
        .nav-menu li a:hover .front,
        .nav-menu li a:hover .back {
            background-color: #51938f;
            background-size: 5px 5px;
            background-size: 5px 5px;
            background-position: 0 0, 30px 30px;
            background-image:linear-gradient(45deg, #478480 25%, transparent 25%, transparent 75%, #478480 75%, #478480),linear-gradient(45deg, #478480 25%, transparent 25%, transparent 75%, #478480 75%, #478480);
            /*只是改变背景，不重要*/
        }
        .nav-menu ul {
            position: absolute;
            text-align: left;
            line-height: 40px;
            font-size: 14px;
            width: 200px;
            -webkit-transition: all 0.3s ease-in;
            -moz-transition: all 0.3s ease-in;
            -ms-transition: all 0.3s ease-in;
            -o-transition: all 0.3s ease-in;
            transition: all 0.3s ease-in;
            -webkit-transform-origin: 0px 0px;
            -moz-transform-origin: 0px 0px;
            -ms-transform-origin: 0px 0px;
            -o-transform-origin: 0px 0px;
            transform-origin: 0px 0px;
            -webkit-transform: rotateX(-90deg);
            -moz-transform: rotateX(-90deg);
            -ms-transform: rotateX(-90deg);
            -o-transform: rotateX(-90deg);
            transform: rotateX(-90deg);
            /*这里-90deg是先把下拉旋转90度，形成隐藏的假象*/
            -webkit-backface-visibility: hidden;
            -moz-backface-visibility: hidden;
            -ms-backface-visibility: hidden;
            -o-backface-visibility: hidden;
            backface-visibility: hidden;
        }
        /*任务九、显示下拉导航菜单，并其设置一个变形效果*/
        .nav-menu > li:hover ul {
            display: block;
            transform:rotateX(0deg);
            /*获取焦点将下拉旋转回正面*/
        }
    </style>
</head>
<body>
<div id="nav">
    <ul class="nav-menu clearfix unstyled">
        <li><a href="#" class="three-d active">
            Home
            <span class="three-d-box"><span class="front">Home</span><span class="back">Home</span></span>
        </a></li>
        <li><a href="#" class="three-d">
            Services
            <span class="three-d-box"><span class="front">Services</span><span class="back">Services</span></span></a>
            <ul class="clearfix unstyled drop-menu">
                <li><a href="#" class="three-d">
                    Html5
                    <span class="three-d-box"><span class="front">Html5</span><span class="back">Html5</span></span>
                </a></li>
                <li><a href="#" class="three-d">
                    Css3
                    <span class="three-d-box"><span class="front">Css3</span><span class="back">Css3</span></span>
                </a></li>
                <li><a href="#" class="three-d">
                    JavaScript
                    <span class="three-d-box"><span class="front">JavaScript</span><span class="back">JavaScript</span></span>
                </a></li>
                <li><a href="#" class="three-d">
                    Videogames
                    <span class="three-d-box"><span class="front">Videogames</span><span class="back">Videogames</span></span>
                </a></li>
            </ul>
        </li>
        <li><a href="#" class="three-d">
            Products
            <span class="three-d-box"><span class="front">Products</span><span class="back">Products</span></span>
        </a></li>
        <li><a href="#" class="three-d">
            About
            <span class="three-d-box"><span class="front">About</span><span class="back">About</span></span>
        </a></li>
        <li><a href="#" class="three-d">
            Contact
            <span class="three-d-box"><span class="front">Contact</span><span class="back">Contact</span></span></a>
            <ul class="clearfix unstyled drop-menu">
                <li><a href="#" class="three-d">
                    Html5
                    <span class="three-d-box"><span class="front">Html5</span><span class="back">Html5</span></span>
                </a></li>
                <li><a href="#" class="three-d">
                    Css3
                    <span class="three-d-box"><span class="front">Css3</span><span class="back">Css3</span></span>
                </a></li>
                <li><a href="#" class="three-d">
                    JavaScript
                    <span class="three-d-box"><span class="front">JavaScript</span><span class="back">JavaScript</span></span>
                </a></li>
                <li><a href="#" class="three-d">
                    Videogames
                    <span class="three-d-box"><span class="front">Videogames</span><span class="back">Videogames</span></span>
                </a></li>
            </ul>
        </li>
        <li><a href="#" class="three-d">
            Blog
            <span class="three-d-box"><span class="front">Blog</span><span class="back">Blog</span></span></a>
            <ul class="clearfix unstyled drop-menu">
                <li><a href="#" class="three-d">
                    Html5
                    <span class="three-d-box"><span class="front">Html5</span><span class="back">Html5</span></span>
                </a></li>
                <li><a href="#" class="three-d">
                    Css3
                    <span class="three-d-box"><span class="front">Css3</span><span class="back">Css3</span></span>
                </a></li>
                <li><a href="#" class="three-d">
                    JavaScript
                    <span class="three-d-box"><span class="front">JavaScript</span><span class="back">JavaScript</span></span>
                </a></li>
                <li><a href="#" class="three-d">
                    Videogames
                    <span class="three-d-box"><span class="front">Videogames</span><span class="back">Videogames</span></span>
                </a></li>
            </ul>
        </li>
        <li><a href="#" class="three-d">
            Shop On-line
            <span class="three-d-box"><span class="front">Shop On-line</span><span class="back">Shop On-line</span></span>
        </a></li>
    </ul>
</div>
</body>
</html>

效果如下：