//CHANGE COLOR OF NAV SERIES BACKGROUND
function changeNavBack(id,status,id_a,num_page){
	if(document.getElementById(id)){
		if(status=='on'){
			document.getElementById('link1').style.backgroundColor='';
			document.getElementById('link2').style.backgroundColor='';
document.getElementById('link3').style.backgroundColor='';
document.getElementById('link4').style.backgroundColor='';

			document.getElementById(id).style.backgroundColor='#000000';
		}else{
			var id_page='link_'+num_page;
			if (id_page != id){
				if(status=='off'){
					document.getElementById(id).style.backgroundColor='';
				}
			}
		}	
	}
}