$(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,'height':maskHeight});   
           
        //transition effect        
        $('#mask').fadeIn(500);       
        $('#mask').fadeTo("slow",0.4);     
       
        //Get the window height and width   
        var winH = $(window).height();   
        var winW = $(window).width();   
                 
        //Set the popup window to center   
        $(id).css('top',  winH/2-$(id).height()/2);   
        $(id).css('left', winW/2-$(id).width()/2);   
       
        //transition effect   
        $(id).fadeIn(500);    
       
    });   
       
    //if close button is clicked   
    $('.window .close').click(function (e) {   
        //Cancel the link behavior   
        e.preventDefault();   
        $('#mask, .window').hide();   
    });           
       
});