The preferences page allows you to configure the system with any system-wide preferences that aren’t directly related to a given tool (e.g, Repetrobes-specific preferences are configured directly in the tool).
A beta version of Dark Mode is currently available. It currently has some glitches but learners need to spend LOTS of time looking at screens (or paper, but we can’t help much with that!), so it is definitely a priority moving forward. Give it a try and let us know about any issues you have we might not have spotted.