body 
{
margin: 0px;
background-color:#dddddd;
}
	
#contenido{ 
   background-color: #dddddd; 
   text-align: center; 
   vertical-align: middle; 
   margin-top: -277px; 
   margin-left: -475px; 
   position: absolute; 
   top: 50%; 
   left: 50%; 
   width: 950px; 
   height: 554px; 
}