function showLightbox(){
	opacity("overlay", 0, 75, 500);
	opacity("lightbox", 0, 100, 500);
}

function hideLightbox(){
	opacity("overlay", 75, 0, 500);
	opacity("lightbox", 100, 0, 500);
}

function opacity(id, opacStart, opacEnd, millisec){
	var speed = Math.round(millisec / 100);
	var timer = 0;
	if(opacStart > opacEnd){
		for(i = opacStart; i >= opacEnd; i--){
			setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer++;
		}
	}else if(opacStart < opacEnd){
		for(i = opacStart; i <= opacEnd; i++){
			setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
			timer++;
		}
	}
}
function changeOpac(opacity, id){
	if(opacity==0){
		document.getElementById(id).style.display="none";
	}else if(opacity==100){
		document.getElementById(id).style.opacity = 100;
		document.getElementById(id).style.filter = "";
		document.getElementById(id).style.display="block";
	}else{
		document.getElementById(id).style.opacity = (opacity / 100);
		document.getElementById(id).style.filter = "alpha(opacity=" + opacity + ")";
		document.getElementById(id).style.display="block";
	}
}