Mac OS X Yosemite offers a new dark mode that is useful for designers who don’t want to be distracted by the bright gray menus standard on Mac OS X. This mode allows the menus to fade into the background where they are less distracting as you work. You can turn on dark mode in Yosemite like this:
1. Select General from the System Preferences menu.
2. Check the box “Use dark menu bar and Dock.”
The menu bar turns dark.
Menus are now transparent, but dark.
And even the Dock is dark.