function jazz() {
	document.getElementById("jazz").style.visibility= "visible"; 
	document.getElementById("django").style.visibility= "hidden"; 
	document.getElementById("swing").style.visibility= "hidden";
	document.getElementById("strumenti").style.visibility= "hidden";
}

function django() {
	document.getElementById("django").style.visibility= "visible"; 
	document.getElementById("jazz").style.visibility= "hidden"; 
	document.getElementById("swing").style.visibility= "hidden";
	document.getElementById("strumenti").style.visibility= "hidden";
}

function swing() {
	document.getElementById("swing").style.visibility= "visible"; 
	document.getElementById("django").style.visibility= "hidden";  
	document.getElementById("jazz").style.visibility= "hidden";
	document.getElementById("strumenti").style.visibility= "hidden";
}

function strumenti() {
	document.getElementById("strumenti").style.visibility= "visible"; 
	document.getElementById("django").style.visibility= "hidden"; 
	document.getElementById("swing").style.visibility= "hidden"; 
	document.getElementById("jazz").style.visibility= "hidden";
}