Dark modes are a low light interface which utilizes darker colors. This can be easier on the eyes in low light environments, emits less blue light, and can demand less power from mobile devices.
Turn to turn-on Dark mode:
Click on the dark/light mode button in the lower left.
Note: If you are trying to customize the colors of certain elements within Plutio, see the Workspace color palette settings below where both light and dark modes can be styled.
How Dark mode appears: