function mostra(capa){
	if(capa=="intro"){
		document.getElementById("intro").style.visibility="visible";
		document.getElementById("cartes").style.visibility="hidden";
		document.getElementById("instruccions").style.visibility="hidden";
		document.getElementById("autors").style.visibility="hidden";
	} else if(capa=="cartes"){
		document.getElementById("intro").style.visibility="hidden";
		document.getElementById("cartes").style.visibility="visible";
		document.getElementById("instruccions").style.visibility="hidden";
		document.getElementById("autors").style.visibility="hidden";
	} else if(capa=="instruccions"){
		document.getElementById("intro").style.visibility="hidden";
		document.getElementById("cartes").style.visibility="hidden";
		document.getElementById("instruccions").style.visibility="visible";
		document.getElementById("autors").style.visibility="hidden";
	} else if(capa=="autors"){
		document.getElementById("intro").style.visibility="hidden";
		document.getElementById("cartes").style.visibility="hidden";
		document.getElementById("instruccions").style.visibility="hidden";
		document.getElementById("autors").style.visibility="visible";
	}
}