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.
iPad Control Center
iOS 7 users can access Control Center from any screen on their device by swiping up from the bottom of their display. This includes the Lock screen, Home screen and even while using games or apps. You can disable access to Control Center from the Lock screen by following the instructions below:
iOS 7 allows users to swipe up from the bottom of their screen to easily access Control Center. This poses a problem when playing games or using apps that also require you swipe up to perform a task.
You can disable the Control Center swipe feature by navigating to Settings > Control Center and tapping the "Access within Apps" slider so it turns white.
Here's a quick look at some the available tweaks in Cydia that will allow you to customize and have more control over your Control Center in iOS 7. All the tweaks listed below require a jailbroken iOS device running iOS 7 to work. You can learn how to jailbreak your device here.
CCControls: Free (ModMyi repo) - The first thing themers are going to want to do is customize their Control Center, and CCControls allows you to do just that! Users can add and remove toggles, change the shape and color of their toggles and decide which toggles can be accessed from the Lock screen. There are currently 24 toggles and 15 stock themes to choose from (with the ability to add more).