function open_menu(){
	var obj = document.getElementById('footerarea');
	var obj2 = document.getElementById('blindtxt');
	obj.className = "close";
    var open_key = obj.style.display;
    if (open_key == 'none') {
        obj.style.display = 'block';
		obj2.innerText = 'サイトマップを非表示';
		obj2.className = "close";
    } else {
        obj.style.display = 'none';
		obj2.innerText = 'サイトマップを表示';
		obj2.className = "open";
    }
}