The notification (also called a "toast") that appears at top of screen after you add a flashcard was a little buggy. It would leave some kind of transparent layer that prevents interacting with whatever it was covering.

After reflection I wasn't satisfied with how that UX works. I'm not fond of how it covers the top of the screen, even temporarily (especially on smartphone). I removed the notification. Instead the confirmation message is shown in place of the Add Card button for a short while, before changing into the "Edit Card" button.

Also, お花見を楽しんでください!