How to theme and change the font of the Arduino IDE (Tutorial)

You've probably had this problem before; Writing code late at night trying to get new features to work but the bright white of the default IDE is burning your eyes and giving you a headache even with F.Lux installed, and/or you've mistaken a "l" for a "1". Well, there are solutions to those problems, but not the other well known problems (autocomplete, not enough debugging features, etc etc) after the break.

Original on left, rethemed and refonted on right