the navigation bar needs to be white to match.
The navigation bar in your screenshot is from the Win8 Metro skin. It was skinned that way. If you want, try a different skin, one which uses a white nav bar.
The guy who skinned the skin you're using apparently wanted it to be off white/gray.
For example, the Win8 skin, by the same person, has a white nav bar.
Moral of story:
Pick a skin with a white nav bar.
Or, you could go into SkinStudio and change the nav bar in Win8 Metro to white, IF you weren't running Windows 10.