I love this concept! My team almost opted to make a deck-builder, and this is a lot like I imagined it could be. The setting and story are fantastic for the jam's theme, and I love the art you've included.
I had a lot of trouble with the UI on my Mac (in browser). The screen was small, couldn't go full screen, and I couldn't see any tool-tips for the cards. I felt like I had little control over the action (just clicking each card, and unsure of if or how the sequence mattered). I think you have ideas here, but they're just not coming through yet.
I'd love to see the Major Arcana play in more in the beginning of the game. We were thinking about cards like "The Fool" having an effect like allowing a redrawn hand, or giving a buff for the rest of the battle, etc. I'd love to have different play throughs with different Major Arcana feel different.
This is a really cool beginning and I hope you continue the work!