window.onload=createLightbox;

function createLightbox()
{
	var lightbox = document.createElement('div');
	lightbox.id = "lightbox";
	lightbox.style.zIndex = 200;
	document.body.appendChild(lightbox);
}
 
 function showLightbox(overlay,display,width,height)
 {
	var centeredHeight = (document.documentElement.clientHeight/2) - height/2 - 45 + document.documentElement.scrollTop;
 	var centeredWidth = (document.documentElement.clientWidth/2) - width/2 + document.documentElement.scrollLeft;
	
	var lightbox = document.getElementById('lightbox');
	lightbox.style.height = document.documentElement.scrollHeight;
	lightbox.style.display = display;
	
	overlay.style.top = centeredHeight;
	overlay.style.left = centeredWidth;
	overlay.style.display = display;
	
	window.scrollTo(0, centeredHeight);
}