function popupReferral() {
  // popup the referral form
  popup ('referral.asp', 'referral_form', 625, 625, 1);
  
}


function popup(url, name, width, height, scrollable) {
  // shows a pop up window
  var left = (screen.width) ? (screen.width-width)/2 : 0;
  var top = (screen.height) ? (screen.height-height)/3 : 0;
  // create the popup settings now
  var settings = 'height='+ height + ',width=' + width + ',top= ' + top + ',left=' + left + ',scrollbars=' + scrollable + ',resizable=no';
  // open the new window
  win = window.open(url, name, settings);
}