function change_message(obj){
	for (var i = 1; i <= 4; i++){
		if (obj == i){
			document.getElementById('message' + i).style.display = 'block';
			document.getElementById('mtitle' + i).style.backgroundPosition = 'bottom';
			document.getElementById('mimg' + i).style.backgroundPosition = 'top';
		}else{
			document.getElementById('message' + i).style.display = 'none';
			document.getElementById('mtitle' + i).style.backgroundPosition = 'top';
			document.getElementById('mimg' + i).style.backgroundPosition = 'bottom';
		}
	}
}