html, body {
  margin: 0;
  height: 100%;
  overflow: hidden;
  background: #fdf6ec;
  /* Small hands rest, drag and double-tap. None of that should scroll the
     page, zoom, or pop a text-selection menu. */
  touch-action: none;
  -webkit-user-select: none;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
  overscroll-behavior: none;
}

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

#start {
  position: fixed;
  inset: 0;
  display: grid;
  place-items: center;
  pointer-events: none;
  animation: breathe 2.4s ease-in-out infinite;
}

#start.gone { display: none; }

@keyframes breathe {
  0%, 100% { opacity: 0.5; transform: scale(1); }
  50%      { opacity: 1;   transform: scale(1.08); }
}

/* Some children are sensitive to motion, and some parents have set this for a
   reason. The toy still works: bubbles appear and fade without pulsing. */
@media (prefers-reduced-motion: reduce) {
  #start { animation: none; opacity: 0.8; }
}