User blog comment:Rupert Giles/Layout Changes: Breakpoints and Typography/@comment--20150417041233/@comment-452-20150419061758

"Hmm, so the images are technically being cut a little aren't they?"

No. They are being shifted.

"Or was it the scroll bar affecting that?"

No. The scrollbar is 16px, and has absolutely nothing to do with it.

"It's not a major issue to lose about 200px of space, but for certain background images it can be crucial."

The idea behind the split background images for fluid is that the same part of the image would always be visible.

The example image is "just" a map, but if it were the characters faces they would be half obscured.