.loader {
    position: fixed;
    z-index: 999;
    top: 50%;
    left: 50%;
    border: 16px solid #f3f3f3;
    border-radius: 50%;
    border-top: 16px solid #3498db;
    width: 120px;
    height: 120px;
    animation: spin 2s linear infinite;
    display: none;
  }
  @keyframes spin {
    0% { transform: translate(-50%, -50%) rotate(0deg); }
    100% { transform: translate(-50%, -50%) rotate(360deg); }
  }