Maybe give them a custom header image, like profiles have. But please don’t encourage them to fill my screen with #FF00FF.
Example:
This is it! We are a real user-eccentric social media!
People spending a looot of time to ruin perfectly good CSS in the most idiosyncratic ways so you can never look at the page without forgetting for even 1 single second that they did that and wondering WHY they were motivated to do so.
I am personally a HUGE fan. There is a big time collaboration between the ability to run wild in this way, and dynamic communities. Compare MySpace vs Facebook. Also on Team Bold Design: tumblr, livejournal and even reddit (after a big fight when they tried to take it away!).
I do also think you gotta have an option to hide all this beautiful wild stuff. Permanently and globally, for specific pages, and temporarily.
One magazine I follow set their background to some busy picture of characters from the game, and it made posts completely unreadable and caused the text menu under comments to disappear.
I hope we get the option not to use magazine cosmetic settings so we can choose to use the default.
There should definitely be an option for users to disable custom themes on a per-magazine basis. I don’t mind them, in general, but some themes can be hard on the eyes, and I’d like to be able to easily just toggle it back to my own default setting.
There should be an option for you to turn the custom CSS off for yourself, rather than disabling the entire feature for the minority of people who don’t like it.
This has been discussed in the kbin matrix channels in the past.
An option to see the default or custom magazine theme is something that will definitely be added.
You can however do some cool stuff with it! (best viewed on a darker theme, or tokyo night :) )