window.onload=init_content;
function show_content(){
	// masquage des autres contenus
	contents=document.getElementById('content').getElementsByTagName('div');
	for(i=0;i<contents.length;i++){
		contents[i].style.display="none";
	}
	//document.getElementById('butterfly').style.display="none";
	document.getElementById('content').style.height="200px";
	document.getElementById('content').style.background="none";
	pname=this.id.substring(6);
	document.getElementById(pname).style.display="block";
}
function init_content(){
	span=document.getElementById('menu').getElementsByTagName('span');
	for(i=0;i<span.length;i++){
		span[i].onclick=show_content;
	}
}