Blender UI colors (and other aspects) can be configured using themes.
Themes settings are contained within XML files that can be edited by hand (if you are a glutton for punishment) or using Blender User Preferences Window, Themes tab.
With the Themes tab you can:
select an existing theme
reset to the Blender Default theme
customize the current theme
load a new theme
save the current theme with a new name
delete the current theme
Select an existing theme
At the top left corner of the User Preferences Window there is a combobox labeled Presets. Click it to open the list and select the theme you prefer. Beware that if you have done modifications to your current theme and have not saved theme, they will be unrecoverably lost if you select another theme.
Reset to the Blender Default theme
Just press the Reset to Default Theme button at the bottom of the window.
Customize the current them