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<style type="text/css">
 .drop-shadow {
    width: 500px;
    height: 300px;
    position: relative;
    background: #ccc;       
  }

  .drop-shadow:before,
  .drop-shadow:after {
    content: "";
    position: absolute;
    z-index: -1;
    bottom: 15px;
    width: 30%;
    height: 20%;
    /*add box-shadow*/
    -webkit-box-shadow: 0 15px 10px rgba(125,125,125,0.8);
    -moz-box-shadow: 0 15px 10px rgba(125,125,125,0.8);
    box-shadow: 0 15px 10px rgba(125,125,125,0.8);
  }
  
  .drop-shadow:before{
    left:5px;	  
    -webkit-transform: rotate(-3deg);
    -moz-transform: rotate(-3deg);
    -o-transform: rotate(-3deg);
    transform: rotate(-3deg);
  }

 .drop-shadow:after {
    right:5px;
    -webkit-transform:rotate(3deg);
    -moz-transform:rotate(3deg);
    -o-transform:rotate(3deg);
    transform:rotate(3deg);
 }