//determines the page name and tags the image with a similar name
function markNav(){
	var url = window.location.pathname;
	url = url.substring(0,url.length - 1);
	var page = url.substring(url.lastIndexOf('/') + 1,url.length - 1);
	if (page.indexOf('.') == -1){
		return;
	}
	page = page.substring(0,page.lastIndexOf('.'));
	
	//change the tags on the images
	$$('img').each(function(img){
		if (img.src.indexOf(page) != -1){
			img.id = "selected";
		}
	});
}