[Plugin: Ultimate Coming Soon Page] Background Image Stretching

Hey so i made a custom background to be displayed and i made it with a resolution of 850×1400. on my laptop it looks great but when i see the coming soon page on my desktop’s 24 inch screen it looks tiled since its not big enough for that screen. is there any way it can stretch it automatically so that no matter what monitor I browse the page in its always centered and positioned correctly? And when i click for the image to be centered as one of the options it always still stays to the left. Thanks in advance.

http://wordpress.org/extend/plugins/ultimate-coming-soon-page/