Invoice Print at front-end overlaps page footer

-- url of the page with the problem -- : www.breffo.gr/demo
-- HikaShop version -- : 2.2.3 Essential
-- Joomla version -- : 3.2
-- PHP version -- : 5.4.24
-- Browser(s) name and version -- : IE11, IE9, Chrome 32.0.1700.x
-- Error-message(debug-mod must be tuned on) -- : N/A

When I go to order listing and choose a 'confirmed' invoice, the invoice that opens, overlaps my page footer. Furthermore, if I press the print button in IE9 (or 11), the invoice preview is shown bellow the page footer.
An example of this is the following (try with username GEORGE/1234).

www.breffo.gr/demo/index.php/hikashop-me...el/order/show/cid-76

You may scroll down until at the bottom of the page and you'll see the footer somewhere on its middle (instead of the bottom). Rest of the site behaves normaly (the footer is always at the bottom). The invoice.php has not changed. Have tested also from different PCs.

Thanks in advance
Charis

Hello Nicolas.

It worked as you said. Put the popup mode in mootools and everything is fine now.

Thank you for your support and prompt response.

Charis