function showNav(linkId, layerName, overClass) {
	showLayer(layerName);
	links = document.getElementById('main-navigation').getElementsByTagName('a');
	for ( var i = 0; i < links.length; i++ ) {
		if ( links[i].className.indexOf('selected') == -1)
			links[i].className = "link" + (i+1);
	}
	link = document.getElementById(linkId);
	link.className = link.className + " " + overClass;
}

function hideNav(linkId, layerName, linkClass) {
	hideLayer(layerName);
	document.getElementById(linkId).className = linkClass;
}

function showLayer(layerName)  { 
	document.getElementById(layerName).style.display='block'; 
}

function hideLayer(layerName)  {  
	document.getElementById(layerName).style.display='none';  
}