if (document.images) {
	var def = new Image();		def.src = "images/hnh_05.png";
	var bef = new Image();		bef.src = "images/hnh_on1_05.png";
	var clu = new Image();		clu.src = "images/hnh_on2_05.png";
	var vol = new Image();		vol.src = "images/hnh_on3_05.png";
	var fun = new Image();		fun.src = "images/hnh_on4_05.png";
}

function tabsOn(tab) {
	eval('document.nav.src = '+tab+'.src');
}
function tabsOff(tab) {
	if (tab != '') {
		eval('document.nav.src = '+tab+'.src');
	} else {
		document.nav.src = def.src;
	}
}