function go_back() {
		var arr = document.getElementsByTagName("kbd");
		for (i = 0; i < arr.length; i++) {
			if (arr[i].className == "here" && i != 0) {
				arr[i].className = "";
				arr[i-1].className = "here";
				i = 999;
			}
		}
	}
	
	function go_forward() {
		var arr = document.getElementsByTagName("kbd");
		for (i = 0; i < arr.length; i++) {
			if (arr[i].className == "here" && i != arr.length-1) {
				arr[i].className = "";
				arr[i+1].className = "here";
				i = 999;
			}
		}
	}
	
	function show_auth() {
		var auth = document.getElementById('auth_box');
		if (auth.className == 'auth_hidden') {
			auth.className = 'auth_visible';
		}
		else {
			auth.className = 'auth_hidden';
		}
	}