Here is an attached screenshot from my iPad Mini Retina showing the Dictionary popup window in Kindle for iOS 4.1. As you can see, part of the window is nearly impossible to read due to light colored, thin font. I hope they fix this. I'm not sure if it is a bug or just a really bad design decision. It might be an iOS 7 thing too, but hopefully it can be fixed.

ETA: Off topic, but I thought you might want to know how I got a light grey background and black text in the Kindle for iOS app. I didn't. I use the standard white background with black text theme, but I turn the backlighting way down on my iPad Mini Retina when reading. I took a screen capture and this is how it came out. In the past screen captures I've made looked white and did not show the low backlighting effect. Interesting effect, and I'm not sure if that is an iOS 7 thing or just an accident. The image is a pretty close rendition of what I see with my eyes when reading in the app.

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