See https://wiki.logos.com/Night_Mode for ways to invert the colors on your PC/Mac, including Logos 6.
I have literally chosen not to open Logos some nights because I don't want to be greeted by a full screen of retina-burn. Native dark mode would make it much more enjoyable to meditate on the Law of the LORD day and night!
Full screen mode is available in Logos 5.
Ditto on both fullscreen and gestures, thanks!
Full screen for Lion