function toggleLayer(whichLayer) {
	var element;
	for (var i = 1; i <= 2; ++i) {
		element = document.getElementById('menu' + parseInt(i));		
		element.className = (i == whichLayer ? 'menu_show' : 'menu_hide');
	}
}

function toggleMain(whichLayer) {
	var element;
	for (var i = 1; i <= 2; ++i) {
		element = document.getElementById('main_menu' + parseInt(i));		
		element.className = (i == whichLayer ? 'main_bold' : 'main_normal');
	}
}