function changeBackgroundOn(page_name){
	var x=document.getElementById(page_name);
	x.style.backgroundColor="transparent";
	x.style.backgroundImage="none";
}
function changeBackgroundOff(page_name){
	var x=document.getElementById(page_name);
	x.style.backgroundColor="#797979";
	x.style.backgroundImage="url('images/over_nav.gif')";
}