* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang HK", sans-serif; background: #fff8e1; color: #222; padding: 10px; max-width: 420px; margin: 0 auto; text-align: center; }
header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 15px; }
h1 { font-size: 1.6rem; }
.big-btn { background: #ffc107; color: #333; border: none; border-radius: 12px; padding: 16px 28px; font-size: 1.3rem; min-height: 56px; cursor: pointer; }
#canvas { background: white; border-radius: 16px; box-shadow: 0 4px 8px rgba(0,0,0,0.1); touch-action: none; margin: 10px auto; }