For Celestial, the core aesthetic is peaceful, with primary and secondary colors being dark and light blue. The variant color is a rich gold, and possibly in some sections a blood red against that. The visuals feature stark white and black, include scenes of darkness as well as bright light. These visuals seek to inspire an air of contemplation, contrast, wonder. Some imagery should be positive and warm, balanced against some of a darker tone.
The major style inspirations are art-nouveau, with ink and watercolor being the main medium.
https://www.pinterest.com/geffenkai/celestial/ (Vibe has most relevant content)
Sandman (Worlds’ End in particular)
Frank Herbert (Water metaphor in particular)
Zen Buddhism
Several different themes are present in the cards in Celestial, with some of those themes more explicitly presented by the playable characters.
Each card has a "flavor text" - some short story which gets across an idea that the card acts as allegory for. These are presented in spoken word to the player when they get each card. Some early ideas for these are written below each theme.
Birds represent letting go and seeking after peace.
Their vignettes center on characters moving beyond obstacles or hardship, and flying free. The moments their images and stories aim to capture is when some character can find personal resolution of some issue that has been keeping them caged, and is now able to fly free. This experience feels positive, but not overly loud. It's a triumph personal to each character, to ascend to that place of peace.