The first part basically lets the image overflow the sides instead of having the bar to scroll. The second part centres the image (that's the margin-left bit - you'll need to edit the number there to fit your image sizes. -96px fits a screen that is 1056p wide). The margin-top part adds a buffer so the arrows show up.
I found a site picresizer.com that did all the work for me and I uploaded all the new images. Also my web page is up! Visit killergin.com, spread the word! Also check out my game and download today! ;0)