function changetab(tab){

	document.getElementById('l_tab').className = 'menu_off';
	document.getElementById('b_tab').className = 'menu_off';
	document.getElementById('t_tab').className = 'menu_off';
	document.getElementById(tab).className = 'menu_on';
	switch(tab){
		case "l_tab":
			document.getElementById('content').innerHTML = document.getElementById('late').innerHTML;
		break;
		case "b_tab":
			document.getElementById('content').innerHTML = document.getElementById('best').innerHTML;
		break;
		case "t_tab":
			document.getElementById('content').innerHTML = document.getElementById('top').innerHTML;
		break;
	}
}