body { margin: 0; padding: 0; }
#container { width: 100%; height: 100%; }
#centering {                 /* we need to know the size of the content area, so we can center it using relative locations and negative margins */
position:absolute; 
width:1024px; 
height:768px; 
left: 50%; 
top: 50%; 
margin-left: -512px; 
margin-top: -384px;
}

#content {                     /* size of the content we're centering */
width:1024px; 
height:768px; 
border:0px solid red;
}


div { border: #000 0px solid; }
#header { width: 1024px; height: 217px; float: left; }
#main-holder { width: 624px; height: 477px; float: left; }
#extra { width: 400px; float: right; }
#main { width: 420px; height: 472px; overflow: auto; float: right; }
#subnav { width: 180px; float: left; }
#footer { width: 1024px; float: left; }