Board Thread:Administrator's Noticeboard/@comment-25428994-20141209201729/@comment-24133975-20141209214542

We can't use the backgrounds you've presented here; we have no permission to do so.

Also, I'm pretty sure that changing the background won't help in fixing the problem, either. It's likely an issue with your browser.

To fix the Mac problem, I think readjusting your browser's current zoom level should do the trick. As for the Kindle, I don't think that can be fixed.