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

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: #1a4d6d;
}

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

#hint {
  position: fixed;
  bottom: 12px;
  left: 50%;
  transform: translateX(-50%);
  font-family: system-ui, sans-serif;
  font-size: 13px;
  color: rgba(255, 255, 255, 0.7);
  background: rgba(0, 0, 0, 0.25);
  padding: 6px 12px;
  border-radius: 6px;
  pointer-events: none;
  transition: opacity 0.8s ease 4s;
}

#hint kbd {
  font-size: 12px;
  padding: 2px 6px;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 4px;
}

#hint.hidden {
  opacity: 0;
  pointer-events: none;
}

#sound-controls {
  position: fixed;
  bottom: 12px;
  left: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: system-ui, sans-serif;
  font-size: 12px;
  color: rgba(255, 255, 255, 0.85);
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid rgba(255, 255, 255, 0.2);
  padding: 6px 10px;
  border-radius: 6px;
  pointer-events: auto;
}

#sound-btn {
  font-size: 12px;
  color: inherit;
  background: transparent;
  border: none;
  padding: 0 4px 0 0;
  cursor: pointer;
  flex-shrink: 0;
}

#sound-btn:hover {
  color: #fff;
}

#volume-label {
  font-size: 11px;
  opacity: 0.9;
  cursor: default;
}

#volume-slider {
  width: 72px;
  height: 6px;
  accent-color: rgba(255, 255, 255, 0.8);
  cursor: pointer;
}

/* YouTube livestream audio only — hidden, no video UI */
#yt-audio {
  position: fixed;
  left: -9999px;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  pointer-events: none;
}