本文主要包含CSS3,阴影等相关知识,trigkit4  希望在学习及工作中可以帮助到您
  效果:
HTML代码:
- <div class="box shadow"></div>
 
CSS代码:
- .box {
 - width: 300px;
 - height: 100px;
 - background: #ccc;
 - border-radius: 10px;
 - margin: 10px;
 - }
 - .shadow {
 - position: relative;
 - max-width: 270px;
 - box-shadow: 0px 1px 4px rgba(0,0,0,0.3),/* 外阴影*/
 - 0px 0px 20px rgba(0,0,0,0.1) inset;/*内阴影*/
 - }
 - .shadow::before,
 - .shadow::after {
 - content:"";
 - position:absolute;
 - z-index:-1;
 - }
 - .shadow::before,
 - .shadow::after {
 - content:"";
 - position:absolute;
 - z-index:-1;
 - bottombottom:15px;
 - left:10px;
 - width:50%;
 - height:20%;
 - }
 - .shadow::before,
 - .shadow::after {
 - content:"";
 - position:absolute;
 - z-index:-1;
 - bottombottom:15px;
 - left:10px;
 - width:50%;
 - height:20%;
 - box-shadow:0 15px 10px rgba(0, 0, 0, 0.7);
 - transform:rotate(-3deg);
 - }
 - .shadow::after{
 - rightright:10px;
 - left:auto;
 - transform:rotate(3deg);
 - }
 
伪元素before和after意思是在被选元素的内容前或后 插入内容

