* {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      min-height: 100vh;
      display: flex;
      justify-content: center;
      align-items: center;
      background: #f3f4f6;
      font-family: Arial, sans-serif;
      color: #111827;
    }

    .card {
      width: 100%;
      max-width: 420px;
      margin: 20px;
      padding: 32px;
      background: white;
      border-radius: 16px;
      box-shadow: 0 8px 30px rgba(0,0,0,0.08);
    }

    h1 {
      margin: 0;
      text-align: center;
      font-size: 32px;
    }

    .subtitulo {
      text-align: center;
      color: #6b7280;
      margin: 8px 0 28px;
    }

    h2 {
      margin: 0 0 20px;
      font-size: 22px;
    }

    label {
      display: block;
      margin-bottom: 6px;
      color: #374151;
      font-size: 14px;
      font-weight: bold;
    }

    input {
      width: 100%;
      padding: 12px;
      margin-bottom: 18px;
      border: 1px solid #d1d5db;
      border-radius: 8px;
      font-size: 16px;
    }

    input:focus {
      outline: none;
      border-color: #111827;
    }

    button {
      width: 100%;
      padding: 13px;
      border: none;
      border-radius: 8px;
      background: #111827;
      color: white;
      font-size: 16px;
      font-weight: bold;
      cursor: pointer;
    }

    button:disabled {
      opacity: 0.6;
      cursor: default;
    }

    .secundario {
      margin-top: 12px;
      background: transparent;
      color: #111827;
      border: 1px solid #d1d5db;
    }

    .link {
      margin-top: 18px;
      text-align: center;
      font-size: 14px;
      color: #4b5563;
    }

    .link button {
      width: auto;
      padding: 0;
      background: transparent;
      color: #111827;
      font-size: 14px;
      text-decoration: underline;
    }

    .mensaje {
      min-height: 20px;
      margin-top: 16px;
      text-align: center;
      font-size: 14px;
      color: #dc2626;
    }

    .mensaje.ok {
      color: #15803d;
    }

    .oculto {
      display: none;
    }

    .pin {
      text-align: center;
      font-size: 28px;
      letter-spacing: 10px;
      font-weight: bold;
    }

    .texto-ayuda {
      color: #6b7280;
      font-size: 14px;
      line-height: 1.5;
      margin-bottom: 18px;
    }