:root {
      --bg: #0f172a;
      --card-bg: #1e293b;
      --accent: #6366f1;
      --text: #f8fafc;
      --text-muted: #94a3b8;
    }

    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
      background-color: var(--bg);
      color: var(--text);
      min-height: 100vh;
      display: flex;
      align-items: center;
      justify-content: center;
      padding: 1.5rem;
    }

    .card {
      background-color: var(--card-bg);
      border: 1px solid rgba(255, 255, 255, 0.08);
      border-radius: 1.25rem;
      padding: 2.5rem;
      max-width: 420px;
      width: 100%;
      text-align: center;
      box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.3), 0 8px 10px -6px rgba(0, 0, 0, 0.3);
    }

    .spinner {
      width: 48px;
      height: 48px;
      border: 4px solid rgba(255, 255, 255, 0.1);
      border-left-color: var(--accent);
      border-radius: 50%;
      margin: 0 auto 1.5rem auto;
      animation: spin 1s linear infinite;
    }

    @keyframes spin {
      to { transform: rotate(360deg); }
    }

    h1 {
      font-size: 1.5rem;
      font-weight: 600;
      margin-bottom: 0.5rem;
    }

    p {
      color: var(--text-muted);
      font-size: 0.95rem;
      margin-bottom: 1.75rem;
      line-height: 1.5;
    }

    .btn {
      display: inline-block;
      width: 100%;
      padding: 0.85rem 1.25rem;
      background-color: var(--accent);
      color: #ffffff;
      font-weight: 500;
      font-size: 0.95rem;
      text-decoration: none;
      border-radius: 0.75rem;
      transition: background-color 0.2s ease, transform 0.1s ease;
    }

    .btn:hover {
      background-color: #4f46e5;
    }

    .btn:active {
      transform: scale(0.98);
    }