$(document).ready(function() {    

    //select all the a tag with name equal to modal  
    $('a[name=modal]').click(function(e) {  
        //Cancel the link behavior  
        e.preventDefault();  
        //Get the A tag  
        var id = $(this).attr('href');  
        //Get the screen height and width  
        var maskHeight = $(document).height();  
        var maskWidth = $(window).width();  

        //Set height and width to mask to fill up the whole screen  
        $('#mask').css({'width':maskWidth*2,'height':maskHeight*2});  

        //transition effect       
        $('#mask').fadeIn(500);      
        $('#mask').fadeTo("slow",0.8);    

        //Get the window height and width  
        var winH = $(window).height();  
        var winW = $(window).width();  
        
        //Set the popup window to center  
        var topPos = winH/2-$(id).height()/2;
        if (topPos < 0) topPos = 0;
        var leftPos = winW/2-$(id).width()/2;
        if (leftPos < 0) leftPos = 0;
        $(id).css('top',  topPos);  
        $(id).css('left', leftPos);  

        //transition effect  
        $(id).fadeIn(1000);   
    });  

    //if close button is clicked  
    $('.window .close').click(function (e) {  
        //Cancel the link behavior  
        e.preventDefault();  
        $('#mask, .window').hide();  
    });       

    //if mask is clicked  
    $('#mask').click(function () {  
        $(this).hide();  
        $('.window').hide();  
    });           
});