Thank for your comment.
Sadly some UI\UX issues come from wrongly chosen theme plate and in browser half of the UI is hidden if not change page resolution or refresh page.
As for bosses, they actually have different behavior and some specific card like 1st boss can shorten player's hand by 1 card, 2nd plays on buffing itself, 3rd operates mostly on poison and debuffs and etc. Perhaps it wasn't unique enough and not noticeable after all, so thanks for pointing this out. We'll think more carefully on game design aspects.