- Board max-width: min(780px, calc(100vh - 160px)) instead of 640px
- Layout max-width: 1200px instead of 900px
- Checkers: 38px base, 42px on large screens
- Dice: 60px on large screens
- Player bars match board width
- Board fills available viewport height
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>