I custom themed my board (using MyBB) and it still validates with no errors and displays properly in all browser types, so I must say I'm not completely lost. Briefly browsing xenForo I noticed: @primaryLighterStill At first I was lost, but I noticed it points to the "color palette". Well, ok I am still a bit stunned. Is this a new form of CSS? Is there anything else I should be aware of? I also noticed: xen: being used in the templates. What does it say? Looks like it will take me a year to theme..