You hate them.
I do, the non-choices Microsoft gives you for themes in Office 2013. White, Light Grey, and Dark Grey are really white, almost white, and a hint of grey.
What to do? Well, there are no perfect solutions, and Microsoft is notorious for ignoring customers. Your one hope is with your desktop theme. Go to Appearance and Personalisation and then to change the theme. Pick a high contrast theme. You’ll get something a whole lot darker, with a bit of colour.