html, body {margin: 0; padding: 0; height: 100%;background: #000000; }  

#wrap { 
position: relative; 
height: 100%;

background: #000000; 
/*margin: 0 auto;  */
/*width: 500px;  */
} 
#content { 
position: absolute; 
top: 50%; 
left: 50%; 
margin-left: -400px;
margin-top:-300px;
/*background: #abc; */
/* text-align: center;  */
}