Is there a list somewhere of the site themes and how to get Hidden ones? In the dashboard you can change your site theme/layout, and I have one Hidden theme. But I thought there were more. Does anyone know how to get them or what they look like? :)

only hidden ones i can recall are the morostide, luminaire and autumn(autumnal) believe they were all rewards for achievements(1000 tie of umpkin deleteri think, one of the fairies ones1k one and believe one the 1k tiers for the red rreignfireside thigs) but cant check to be certain as clicking the stars on those dont tell me

lol i've been aiming to finally unlock all of these this year, so yeah, as says autumn/fireside is unlocked by hitting the 1000 tier of Item Giver (throwing items to the red rreign during fireside) and luminaire is unlocked by hitting the 1000 tier for Free All The Fairies! however, the morostide theme is actually unlocked by hitting the 500 tier of the Carve a Pumpkin achievement (confusing as the other ones are 1000, but i guess the carving one doesn't actually have a 1000 tier!). the subeta wiki has previews of the themes.

they don't show up on the achievements page as unlockable this way so it is a bit confusing.

actually the fact that an achievement has a star to indicate a reward, but clicking on it fails to reveal the reward, IS how you know the reward is a hidden theme. perhaps unintentional but that's the only reward type that behaves that way so there's no mistaking it.