In iOS 8, when you had the Books app set to black background and the backlight all the way down it was pretty much black, about as much as LCD can get. In iOS 9 it appears some Apple bozo thought it would be nice if black was not quite black but a dark gray instead. So now Books in a completely dark room, in Night mode, is not black at all and emits significantly more light. Just what you don't want in a night-reading mode. It looks like crappy backlight leakage from an original iPhone with a poor black level LCD, but this is an iPhone 6 Plus. Once again form over function. NOT HAPPY. Thanks, Apple!! EDIT: If you set the background to white and have triple-click set to invert your screen, you do get a true black background, but the text itself is a brighter white. And it's inconvenient.