function mostra(idioma){
	document.getElementById('menu').style.visibility = 'hidden';
	document.getElementById('menu_ca').style.visibility = 'hidden';
	document.getElementById('menu_es').style.visibility = 'hidden';
	document.getElementById('menu_en').style.visibility = 'hidden';
	document.getElementById('menu_'+idioma).style.visibility = 'visible';
}