function vdo_demo(){
    document.getElementById('flash_box').className = 'vdo_box_on';
    mask_aff_fond('');
}
function vdo_demo_close(){
    document.getElementById('flash_box').className = 'vdo_box_off';
    mask_aff_fond('none');
}
function mask_aff_fond(type_aff){
    fond_vdo = document.getElementById('fond');
    var largeur_vdo = (screen.availWidth);
    //var hauteur_vdo = (screen.availHeight);
    //indice = document.getElementById('flash_box').style.width;
    pos_x = (largeur_vdo/2)-(320);//640/2 largeur du div;
    document.getElementById('flash_box').style.marginLeft = pos_x+'px';
    //alert('indice '+indice+' pos_x'+pos_x);
	if (navigator.appName.indexOf("Microsoft Internet") != -1 && type_aff == 'none' ){
	    urlPage = document.location;
	    document.location = urlPage;
	}
    if(fond_vdo)
      {
      with(fond_vdo.style)
        {
        position="absolute";
        display=type_aff;
        left = "0px";
        top  = "0px";
        height = "1800px";
        zIndex= "10";
        }
      }
}