html, body { margin: 0; height: 100%; background: #2b2f3a; overflow: hidden; touch-action: none; }
  body { display: flex; align-items: center; justify-content: center; font-family: system-ui, sans-serif; }
  canvas { display: block; background: #fbf8ec; border-radius: 10px; box-shadow: 0 8px 40px rgba(0,0,0,.5); touch-action: none; }