.viewer {  
  margin: 0 auto;  
  width: 530px;  
  height: 235px;  
  text-align: left;  
  overflow: hidden;  
 }  

.viewer ul {  
  width: 530px;  
  height: 235px;  
  text-align: left;  
  overflow: hidden;  
  position: relative;  
 }  

.viewer ul li {  
  top: 0;  
  left: 0;  
  width: 530px;  
  height: 235px;  
  display: none;  
  position: absolute;  
 }