BODY { 
  background: red url("back.gif");
  background-repeat: repeat-y;
  background-attachment: fixed;
  background-position: center;
}

/*************************************
Google Ads Vak Rechts (buiten content)
**************************************/
.google_ad_rechts {
width: 160px;
height: 600px; 
left: 50%;
margin-left: 350px; /* - (width/2) */
margin-top: 280px;
position: absolute;
}

/*************************************
Google Ads Vak Links (buiten content)
**************************************/
.google_ad_links {
width: 160px;
height: 600px; 
right: 50%;
margin-right: 351px; /* - (width/2) */
margin-top: 275px;
position: absolute;
}