body {
      margin: 0;
      display: flex;
      align-items: center;
      justify-content: center;
      min-height: 100vh;
      background: #0f0f0f;
      font-family: sans-serif;
      color: #fff;
    }
    .spinner {
      width: 36px;
      height: 36px;
      border: 3px solid rgba(255,255,255,0.15);
      border-top-color: #fff;
      border-radius: 50%;
      animation: spin 0.7s linear infinite;
    }
    @keyframes spin { to { transform: rotate(360deg); } }