While you can’t adjust the IDE color scheme, you can quickly toggle the navigator, debug area, and utility views with the following commands:
Navigator : ⌘0
Debug Area : ⇧⌘Y
Utility : ⌥⌘0
So, if you set your theme to one with a dark background, you can quickly close/open the lighter portions of the IDE as needed.
You can also change the debug console to have a different background by going into preferences ⌘., then go to Fonts & Colors, then select the Console. Now you can edit its background:
Just be sure to edit the font colors of the various input and outputs texts if you choose black. By default all of the input/output fonts are black, only the console prompt is not.