#playPauseBtn {
      position: fixed;
      bottom: 20px;
      left: 20px;
      background: rgba(15,32,39,0.75);
      color: rgba(0,247,255,0.2);
      border: none;
      border-radius: 50%;
      width: 50px;
      height: 50px;
      font-size: 22px;
      cursor: pointer;
      display: none; /* caché au départ */
      box-shadow: 0 4px 10px rgba(0,0,0,0.5);
      transition: transform 0.2s ease;
}
#playPauseBtn:hover {
      transform: scale(1.1);
}