body {
      font-family: Arial, sans-serif;
      background: #f4f4f4;
      display: flex;
      justify-content: center;
      align-items: center;
      height: 100vh;
      margin: 0;
    }
    .container {
      background: white;
      padding: 20px;
      border-radius: 10px;
      box-shadow: 0 0 10px rgba(0,0,0,0.1);
      width: 300px;
      text-align: center;
    }
    input {
      width: 90%;
      margin: 5px 0;
      padding: 8px;
      border: 1px solid #ccc;
      border-radius: 5px;
    }
    button {
      width: 95%;
      padding: 10px;
      background: #4CAF50;
      color: white;
      border: none;
      border-radius: 5px;
      cursor: pointer;
      margin-top: 10px;
    }
    button:hover { background: #45a049; }
    .hidden { display: none; }
    .link { color: blue; text-decoration: underline; cursor: pointer; }