function masque_plan() {
	document.getElementById('plan').style.display="none";
	document.getElementById('fond_plan').style.display="none";
}

function affiche_plan() {
	document.getElementById('plan').style.display="block";
	document.getElementById('fond_plan').style.display="block";
}

function affiche_plan2() {
	document.getElementById('plan2').style.display="block";
	document.getElementById('fond_plan').style.display="block";
}