function change_img(id,img) {
		if(id<7) {hide_all(); }
		var bild = document.getElementById(id);
		bild.src = "assets/"+img;
		
		if(id==2) {
			var sn1 = document.getElementById("subnavi1");
			sn1.style.display = "block";
		}
		if(id==3) {
			var sn2 = document.getElementById("subnavi2");
			sn2.style.display = "block";
		}
	}
	function hide_all() {
		var sn1 = document.getElementById("subnavi1");
		var sn2 = document.getElementById("subnavi2");
		sn1.style.display = "none";
		sn2.style.display = "none";
	}	
	function show_stress() {
		var s = document.getElementById("stress");
		s.style.visibility = "visible";
	}
	function hide_stress() {
		var s = document.getElementById("stress");
		s.style.visibility = "hidden";
	}