function block_toplayer() {

	ns4 = (document.layers)? true:false;
	ie4 = (document.all)? true:false;
	nc6 = (typeof(window.controllers) != 'undefined' && typeof(window.locationbar) != 'undefined')? true:false;
	isW3C = (document.getElementById) ? true : false
	
	if (ie4) {
		largeur = document.body.clientWidth - 300;
		splash_layer.style.visibility = 'hidden' ;
		splash_layer.style.width = largeur;
		//splash_layer.style.marginRight= -15; 
		top_layer.style.width = largeur;
		top_layer.style.pixelTop = document.body.scrollTop;
		top_layer.style.pixelLeft = document.body.scrollLeft +250;
		//top_layer.style.visibility = 'visible' ;
		//top_layer.style.marginRight= -15; 
		help_layer.style.width = 400 ;
		help_layer.style.pixelTop = 90 + document.body.scrollTop ;
		help_layer.style.pixelLeft = 400; 
		}

	if (ns4) {
		largeur = window.innerWidth - 300;
		document.splash_layer.visibility = 'hidden' ;
		document.top_layer.visibility = 'visible' ;
		document.top_layer.width = largeur ;
		document.top_layer.top = window.pageYOffset;
		document.top_layer.left = window.pageXOffset+250;
		document.help_layer.width = 400 ;
		document.help_layer.top = 90 + window.pageYOffset;
		document.help_layer.left = 400;

		}

	if (nc6) {
		largeur = window.innerWidth - 300;
		document.getElementById('splash_layer').style.visibility = 'hidden';
		document.getElementById('top_layer').style.visibility = 'visible';
		document.getElementById('top_layer').style.width = largeur;
		document.getElementById('top_layer').style.top = window.pageYOffset;
		document.getElementById('top_layer').style.left = window.pageXOffset+250;
		document.getElementById('help_layer').style.width = 400 ;
		document.getElementById('help_layer').style.top = 90+ window.pageYOffset;
		document.getElementById('help_layer').style.left = 400;

		}
	if (!ie4 && !nc6 && !ns4) {
		largeur = window.innerWidth - 300;
		document.getElementById('splash_layer').style.visibility = 'hidden';
		document.getElementById('top_layer').style.visibility = 'visible';
		document.getElementById('top_layer').style.width = largeur;
		document.getElementById('top_layer').style.top = window.pageYOffset;
		document.getElementById('top_layer').style.left = window.pageXOffset+250;
		document.getElementById('help_layer').style.width = 400 ;
		document.getElementById('help_layer').style.top = 90+ window.pageYOffset;
		document.getElementById('help_layer').style.left = 400;
		}

	setTimeout("block_toplayer()",0);
	}