how to add dynamic height to overlay in jquery dialog box code example

Example: how to add dynamic height to overlay in jquery dialog box

function showDialog(title, content) {
                var height = $(document).height();
                $("#message").dialog({
                    modal: true,
                    width: "auto",
                    position: {my: 'top', at: 'top'},
                    buttons: {
                        Ok: function () {
                            $(this).dialog("close");
                        }
                    },
                    open: function (event, ui) {
                        $(".ui-dialog-titlebar-close", ui.dialog | ui).hide();
                        $('.ui-widget-overlay').css('height',height);
                    }
                });
            }