Using MAMP I have installed a local instance of Joomla 3.2.3 with the Rockettheme Leviathan template which uses the same module class suffix scheme and with OS ImageGallery Pro in the same module position and get the same result, ie, the suffixes rt-bevel, nomarginleft and nomargintop do not work.
In both installations I have tried different module positions and tested using different browsers all with the same result.
Further testing shows that the only module class suffixes that work with OS ImageGallery Pro are box1, box2, box3, box4, box5 and box6 and the remainder of the module class suffixes described at demo.rockettheme.com/live/joomla/oculus/...es/module-variations
I have attached in image to show how it looks and how it should look with the expanded black background.
I have forwarded FTP and admin access details through your contact form.
Thank you for your assistance.