.loader {
      border: 8px solid #f3f3f3;
      border-top: 8px solid #3498db;
      border-radius: 50%;
      width: 100px;
      height: 100px;
      animation: spin 2s linear infinite;
      margin-bottom: 20px;
      margin: auto;
  }
  @keyframes spin {
      0% { transform: rotate(0deg); }
      100% { transform: rotate(360deg); }
  }