Today we've upgraded the software to reinstate two popular themes that many people used before the upgrade to version 6 of our forum software.
"Colorplay" is a dark theme in multiple colors, and "Nexus" is a light theme in similar color variations.
If anyone sees any issues with them please let me know and I will report them to the developer.
The only thing I note so far is that on a desktop the "user control panel" with the notifications list at the top right of the screen is not "sticking" as you scroll down the screen, and it disappears off the top til you scroll back to the top. The developer had the same issue with the "ambience" theme when we added that, and he fixed it promptly, so that should be resolved soon too.
Mostly these introduce just subtle changes in colors, rather than any additional features, so if you're happy with your current style there's no reason to change.