To go with the new forum software, there is now also a new theme! Made in Civ (6) style.
Let me know what you think and perhaps we can make adjustments.
One thing I would like to ask you guys for, this has a background picker. You can choose your own background (as I understand it) from available backgrounds. Currently that's only one. If you have good additions, that are also in style of this forum, let me know, pass me a link and I'll try to make it happen.
You can still go back to the old theme, scroll all the way down. In the bottom-left there is the word "Theme". Click it and select default.