Since cards are automatically reshuffled when you run out, I wanted to avoid players have too few cards in their decks since it would be too easy to just "recycle" your most powerful cards. So that's why I required that 5 cards be added to your deck after each match. I'll probably let the player just pick OK at the reward screen but only if they have more than 100 cards.

Thanks for pointing out the music volume bug, unfortunately it wasn't tested much (I always played with 100% music and sound volume). It seems to occur only whenever a new track plays. I'll try to have a fix for this in a future version.