function insertOverlayCode() {
	$$('body')[0].insert(['',
		'<div id="overlay-background" style="display:none;"></div>',
		'<div id="overlay-holder" style="display:none;">',
			'<div id="overlay-foreground" style="display:none;">',
			'</div>',
		'</div>'
		].join(''));
}

function clearOverlay() {
	$('overlay-foreground').hide();
	$('overlay-background').fade({duration:.5});
	$('overlay-holder').hide();
}

function showOverlay(element, width, height) {
	
	$('overlay-foreground').setStyle({
		width: width + 'px',
		left: getOffset('left', width, height) + 'px',
		top: getOffset('top', width, height) + 'px',
		position: 'absolute'
	});
	
	$('overlay-background').setStyle({	
		height: (document.height || document.body.offsetHeight) + 'px'
	});	
	
	
	$('overlay-foreground').innerHTML = '<div><a href="javascript:clearOverlay();"><img src="images/close_button.gif" border="0" alt="Close" /></a></div>';

	$('overlay-foreground').innerHTML += '<img src="images/full_images/image' + element + '.jpg" onclick="clearOverlay();"  />';	
	
	
	$('overlay-background').show();
	$('overlay-holder').show();				
	$('overlay-foreground').appear({duration:.5});

}

function getOffset(dimension, _width, _height) {
	var ybounds = document.viewport.getHeight();
	var xbounds = document.viewport.getWidth();

	var offset = 0;
	if (typeof(window.pageYOffset) == 'number') {
		offset = window.pageYOffset;
	} else if (document.body && document.body.scrollTop){
		offset = document.body.scrollTop;
	} else { 
		offset = document.documentElement.scrollTop;
	}
	
	if (dimension == 'top') {
		var top = Math.floor(( ybounds - _height ) / 2) + (offset - 50);
		return top;
	} else {
		var left = Math.floor(( xbounds - _width ) / 2);		
		return left;
	}
}