The box lid combined width:100% with 2.6rem side padding and no box-sizing reset, so the card ran off the right edge of real phones (Join, Play Here, and Claim all clipped). A global border-box reset fixes the class of bug; the hotseat and claim rows now wrap, their inputs go full-width on narrow screens, and the lid tightens its padding and title below 900px. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>