Margins

I’ve designed a Directors Treatment using readymags and have a very annoying issue. On the right hand side of the screen, the entire way down the scrolling layout, there is a gap. It doesn’t matter how I anchor images, or place them, there is always a gap when previewing and publishing the site. On edit mode, the images go right up to the edge of the screen and work fine. I’ve tried playing around with anchoring widgets/extending them beyond the boundary/setting the background to black to temporarily solve the issue. But all images don’t reach the edge of the page. Anyone have any ideas?