利用CSS伪元素 ：before 和 ：after 可以在文档前后插入内容而不改变文档原有结构，再配合 box-shadow 可以实现很炫的效果,
3、利用 :before, :after, box-shadow 实现照片叠加效果.
<!DOCTYPE html>
<html lang="zh-cn">
<head>
<title>Pseudo Demo</title>
<style>
body{background-color:#ccd3d7;padding:40px;}
h2{display:block;border-bottom:1px solid #ddd;padding:15px;}
p.myquote{padding:1em;font-size:16px;margin:8px 1em;position:relative;color:blue;line-height:1.7em;}
p.myquote:before,p.myquote:after{font-size:40px;position:absolute;padding:0;margin:0;color:green;}
p.myquote:hover:before,p.myquote:hover:after{color:red;font-size:50px;}
p.myquote:before{content:"“";left:0;left:-10px;}
p.myquote:after{content:"”";padding-left:15px;bottom:4px;}
.shbox{
background:#fff;
padding:10px;
width:90%;
margin:40px auto;
height:auto;
margin:40px auto;
}
.sh-down-lr{position:relative;}
.sh-down-lr:before,.sh-down-lr:after{
z-index: -1;
position: absolute;
content: "";
bottom: 15px;
left: 10px;
width: 50%;
top: 80%;
max-width:300px;
background: #777;
-webkit-box-shadow: 0 15px 10px #777;
-moz-box-shadow: 0 15px 10px #777;
box-shadow: 0 15px 10px #777;
-webkit-transform: rotate(-3deg);
-moz-transform: rotate(-3deg);
-o-transform: rotate(-3deg);
-ms-transform: rotate(-3deg);
transform: rotate(-3deg);
}
.sh-down-lr:after{
-webkit-transform: rotate(3deg);
-moz-transform: rotate(3deg);
-o-transform: rotate(3deg);
-ms-transform: rotate(3deg);
transform: rotate(3deg);
right:10px;
left:auto;
}
.stackone {
border: 6px solid #fff;
width: 400px;
height:225px;
margin: 50px;
position: relative;
-webkit-box-shadow: 2px 2px 5px rgba(0,0,0,0.3);
-moz-box-shadow: 2px 2px 5px rgba(0,0,0,0.3);
box-shadow: 2px 2px 5px rgba(0,0,0,0.3);
}
.stackone img{width:100%;heigth:100%;}
.stackone:before,.stackone:after {
content: "";
width: 400px;
height:225px;
background: #aaa;
border: 6px solid #fff;
position:absolute;
z-index:-1;
top:0;
left:-10px;
-webkit-box-shadow: 2px 2px 5px rgba(0,0,0,0.3);
-moz-box-shadow: 2px 2px 5px rgba(0,0,0,0.3);
box-shadow: 2px 2px 5px rgba(0,0,0,0.3);
-webkit-transform: rotate(-5deg);
-moz-transform: rotate(-5deg);
-o-transform: rotate(-5deg);
-ms-transform: rotate(-5deg);
transform: rotate(-5deg);
}
.stackone:after {
top:5px;
left:0;
-webkit-transform: rotate(3deg);
-moz-transform: rotate(3deg);
-o-transform: rotate(3deg);
-ms-transform: rotate(3deg);
transform: rotate(3deg);
}
</style>
</head>
<body>
<div class="shbox sh-down-lr">
<h2>CSS Demo :before, :after, box-shadow</h2>
<p class="myquote">人最宝贵的是生命。生命属于人只有一次。人的一生应当这样度过：当回忆往事的时候，他不会因为虚度年华而悔恨，也不会因为碌碌无为而羞愧.</p>
<p class='myquote'>钢是在烈火里燃烧、高度冷却中炼成的，因此它很坚固。我们这一代人也是在斗争中和艰苦考验中锻炼出来的，并且学会了在生活中从不灰心丧气。</p>
</div>
<div class="shbox" style="background:none;">
<div class="stackone">
<img src="http://photos.tuchong.com/392707/f/6512410.jpg" />
<div>
</div>
</body>
</html>