.loading {
    position: absolute;
    top: 50%;
    left: 50%;
  }
  .loading-bar {
    display: inline-block;
    width: 4px;
    height: 18px;
    border-radius: 4px;
    animation: loading 1s ease-in-out infinite;
  }
  .loading-bar:nth-child(1) {
    background-color: #3498db;
    animation-delay: 0;
  }
  .loading-bar:nth-child(2) {
    background-color: #c0392b;
    animation-delay: 0.09s;
  }
  .loading-bar:nth-child(3) {
    background-color: #f1c40f;
    animation-delay: .18s;
  }
  .loading-bar:nth-child(4) {
    background-color: #27ae60;
    animation-delay: .27s;
  }
  
  @keyframes loading {
    0% {
      transform: scale(1);
    }
    20% {
      transform: scale(1, 2.2);
    }
    40% {
      transform: scale(1);
    }
  }