$(document).ready(function(){

    //get the height and width of the page
    var window_width = $(window).width();
    var window_height = $(window).height();

    var document_height = $(document).height();
	$('#mask').css({ 'width' : window_width, 'height' : document_height });

    //vertical and horizontal centering of modal window(s)
    /*we will use each function so if we have more then 1
    modal window we center them all*/
    $('.modal_window').each(function(){

        //get the height and width of the modal
        var modal_height = $(this).outerHeight();
        var modal_width = $(this).outerWidth();


        //calculate top and left offset needed for centering
        var top = ((window_height-modal_height)/2);
        var left = (window_width-modal_width)/2;

        //apply new top and left css values
        $(this).css({'top' : top , 'left' : left});

    });

        $('.activate_modal').click(function(){

              //get the id of the modal window stored in the name of the activating element
              var modal_id = $(this).attr('name');

              //use the function to show it
              show_modal(modal_id);

        });

        $('.close_modal').click(function(){

            //use the function to close it
            close_modal();

        });

    });

    //THE FUNCTIONS

    function close_modal(){
		var window_pageYOffset = document.documentElement.scrollTop;//window.pageYOffset//document.body.scrollTop

        //hide the mask
        $('#mask').fadeOut(1000);

        //hide modal window(s)
        $('.modal_window').fadeOut(1000);

        window.setTimeout("window.scrollTo(0, " + window_pageYOffset + ")", 1);

    }

    function show_modal(modal_id){
		var window_pageYOffset = document.documentElement.scrollTop;//window.pageYOffset//document.body.scrollTop
		var window_height = document.body.clientHeight;
		var modal_height = $('#'+modal_id).outerHeight();
		var top = ((window_height-modal_height)/2)+window_pageYOffset;
		//top = window_pageYOffset;
		//alert(window_pageYOffset);

        $('#'+modal_id).css({'top' : top});

        //set display to block and opacity to 0 so we can use fadeTo
        $('#mask').css({ 'display' : 'block', opacity : 0});

        //fade in the mask to opacity 0.8
        $('#mask').fadeTo(1000,0.8);

         //show the modal window
        $('#'+modal_id).fadeIn(1000);

    }