Modal pop up window to fit within browser view if resize height

gistfile1.txt

$(function(){
    $(window).resize(function(){
    // get the screen height and width  
    var maskHeight = $(window).height();  
    var maskWidth = $(window).width();

    // calculate the values for center alignment
    var dialogTop =  (maskHeight  - $('#dialog-box').height())/2;  
    var dialogLeft = (maskWidth - $('#dialog-box').width())/2; 

    // assign values to the overlay and dialog box
    $('#dialog-overlay').css({ height:$(document).height(), width:$(document).width() }).show();
    $('#dialog-box').css({ top: dialogTop, left: dialogLeft, position:"fixed"}).show();
    }).resize();
});

http://jsfiddle.net/tF8TU/2/