I have noticed that a few sites that use Xenforo for their forums allow their premium users to select between a few predefined custom css options for their post stylings.
An example I will use is Squidboards.
In this image you can see that these two premium users have selected two different defined settings for their css.
My question is how would I go about implementing something similar? Would I use custom user fields somehow? Is there a resource I have not seen yet?