Both the Notification Center and Control Center in iOS 8 have a transparent look that allows the colors in the background on your Home screen to bleed through. You can disable this to increase legibility by navigating to to Settings > General > Accessibility > Increase Contrast. From here, just tap the "Reduce Transparency" slider so it appears OFF / White. This will turn your Notification Center a solid black and your Control Center a solid gray.
How do I improve the contrast of Notification Center or Control Center on my iPad?
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