/* The existing web viewer YouTube sound prompt, reused by Reveal videos. */
.web-sound-hint { position: fixed; z-index: 7; left: 50%; bottom: calc(170px + env(safe-area-inset-bottom, 0px)); transform: translateX(-50%);
  background: #fff; color: #0F133A; padding: 14px 22px; border: none; border-radius: 28px; font: 600 16px/1 'Roboto', sans-serif; white-space: nowrap;
  pointer-events: none; box-shadow: 0 4px 18px rgba(0, 0, 0, .45); animation: web-sound-pulse 1.6s ease-in-out infinite; }
.web-sound-hint[hidden] { display: none; }
@keyframes web-sound-pulse { 0%, 100% { transform: translateX(-50%) scale(1); } 50% { transform: translateX(-50%) scale(1.07); } }
.reveal-sound-hint { position: absolute; pointer-events: auto; z-index: 4; }
@media (prefers-reduced-motion: reduce) { .web-sound-hint { animation: none; } }