body {
  background: black;
}

@keyframes thumbnail {
  0% {
    opacity: 1;
  }
  100% {
    opacity: 0;
  }
}
.thumbnail {
  animation: thumbnail 1s 10s forwards;
  position: absolute;
  z-index: -1;
  width: 100%;
  left: 0;
  top: 50%;
  pointer-events: none;
  opacity: 1;
  transform: translateY(-50%);
}

#bg-audio {
  position: fixed;
  bottom: 0;
  right: 0;
  z-index: 9999; /* ensures it stays in front */
  background-color: rgba(255, 255, 255, 0.7); /* optional for visibility */
}