https://www.hebrewsongs.com/resources/js/libs/popup.js

1$(document).ready(function() {	
2
3		var id = '#dialog';
4	
5		//Get the screen height and width
6		var maskHeight = $(document).height();
7		var maskWidth = $(window).width();
8	
9		//Set heigth and width to mask to fill up the whole screen
10		$('#mask').css({'width':maskWidth,'height':maskHeight});
11		
12		//transition effect		
13		$('#mask').fadeIn(500);	
14		$('#mask').fadeTo("slow",0.9);	
15	
16		//Get the window height and width
17		var winH = $(window).height();
18		var winW = $(window).width();
19              
20		//Set the popup window to center
21		$(id).css('top',  winH/2-$(id).height()/2);
22		$(id).css('left', winW/2-$(id).width()/2);
23	
24		//transition effect
25		$(id).fadeIn(2000); 	
26	
27	//if close button is clicked
28	$('.window .close-popup').click(function (e) {
29		//Cancel the link behavior
30		e.preventDefault();
31		
32		$('#mask').hide();
33		$('.window').hide();
34	});		
35	
36	//if mask is clicked
37	$('#mask').click(function () {
38		$(this).hide();
39		$('.window').hide();
40	});		
41	
42});