See https://wiki.logos.com/Night_Mode for ways to invert the colors on your PC/Mac, including Logos 6.Kevin O'Connor commented
I would also please request a dark mode. It means that we can use Logos late at night etc. and reduce overall eye strain.
Please - this is an important feature, not just as 'nice to have'.
I appreciate it takes a lot of work from the coding side of things, but it would be great to have this.