function change_menu(id){
	url = './page/'+id+'.html';
	container = 'intro_content';
	new Ajax.Updater(container,url,{method:'get'});
}
function change_php(id){
	url1 = './page/'+id+'.php';
	container1 = 'intro_content';
	new Ajax.Updater(container1,url1,{method:'get'});
}

function showcontent(id){
	var obj_id = document.getElementById(id);
	if(obj_id.style.display == 'none'){
		obj_id.style.display = 'block';	
	}else{
		obj_id.style.display = 'none';	
	}
}

function showpage(id1,id2){
	var obj_id1 = document.getElementById(id1);
	var obj_id2 = document.getElementById(id2);
	obj_id1.style.display = 'none';
	obj_id2.style.display = 'block';
}