*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: #000;
  font-family: system-ui, sans-serif;
  color: #fff;
  touch-action: none;
  -webkit-tap-highlight-color: transparent;
}

#canvas {
  display: block;
  width: 100%;
  height: 100%;
}

.back {
  position: fixed;
  top: max(0.75rem, env(safe-area-inset-top));
  left: max(0.75rem, env(safe-area-inset-left));
  z-index: 10;
  padding: 0.4rem 0.65rem;
  background: rgba(0,0,0,0.45);
  color: #ddd;
  text-decoration: none;
  font-size: 0.85rem;
  border-radius: 8px;
}

.hint {
  position: fixed;
  bottom: max(0.9rem, env(safe-area-inset-bottom));
  left: 50%;
  transform: translateX(-50%);
  z-index: 10;
  font-size: 0.78rem;
  color: rgba(255,255,255,0.45);
  pointer-events: none;
  white-space: nowrap;
}