@keyframes ring {
        0%,
        100% {
          transform: rotate(0deg);
        }
        10%,
        30%,
        50%,
        70%,
        90% {
          transform: rotate(2deg);
        }
        20%,
        40%,
        60%,
        80% {
          transform: rotate(-2deg);
        }
      }
      .ringing {
        animation: ring 1s infinite;
      }
      .red-hangup {
        background-color: #e53935 !important;
        color: white !important;
        border: none;
      }
      .green-answer {
        background-color: #22c55e !important;
        color: white !important;
        border: none;
      }