body {
      font-family: 'Segoe UI', sans-serif;
      background: #111827;
      color: #f3f4f6;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100vh;
      padding: 20px;
    }

    h1 {
      font-size: 2rem;
      margin-bottom: 20px;
    }

    .card {
      background: #1f2937;
      padding: 20px;
      border-radius: 12px;
      box-shadow: 0 0 10px rgba(0,0,0,0.5);
      width: 320px;
      text-align: center;
    }

    input, select, button {
      width: 100%;
      padding: 10px;
      margin-top: 10px;
      margin-bottom: 15px;
      border-radius: 8px;
      border: none;
      font-size: 1rem;
    }

    button {
      background: #3b82f6;
      color: white;
      cursor: pointer;
      transition: background 0.2s ease-in-out;
    }

    button:hover {
      background: #2563eb;
    }

    .result {
      margin-top: 15px;
      font-size: 1.2rem;
      color: #22d3ee;
    }

    a {
      margin-top: 25px;
      color: #60a5fa;
      text-decoration: none;
      display: inline-block;
    }

    a:hover {
      text-decoration: underline;
    }