html,body {
   margin:0;
   padding:0;
   height:100%; /* needed for #wrapper min-height */
}
 
#wrapper {
   height:auto !important; /* real browsers */
   height:100%; /* IE6: treaded as min-height*/
   position:relative;
   min-height:100%; /* real browsers */
}
 
#content_bb {
   margin-bottom: 6em; /* some space for the footer */
}
 
#footerpos {
   position: absolute; 
   bottom: 0px; /* stick it to the bottom */
}