function open_niveau(){
  var page="niveau-service.php?TB_iframe=true&height=450&width=700";
  open_thickbox(page);
}
function open_mentions(){
  var page="mentions-legales.php?TB_iframe=true&height=450&width=700";
  open_thickbox(page);
}

function open_thickbox(page){
  var t = null;
  var a = page;
  var g = false;
  tb_show(t,a,g);
}