The Kindle's screen is intended to be easily read without straining the eyes, under a variety of lighting conditions. Because of the text's appearance, the Kindle reader cannot make any adjustments to the text and visibility other than the brightness. The Kindle app for iPad, however, can invert the text appearance from black-on-white to white-on black. The switch makes the device even easier to read in total darkness.
Tap to open the Kindle app on the iPad.
Tap and select the book you want to read.
Tap the "AA" button to open the Text menu. Tap "White" to invert the background and text colors from black to white.