body {
  font-family: "Segoe UI", sans-serif;
  margin: 0;
  padding: 0;
  background-color: #f2f4f8;
  color: #333;
}

.container {
  max-width: 600px;
  margin: auto;
  padding: 20px;
}

.card {
  background-color: #fff;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  padding: 20px;
  margin-top: 20px;
}

.card h2 {
  margin-top: 0;
  font-size: 1.4rem;
  margin-bottom: 10px;
}

.field {
  margin-bottom: 12px;
}

.field label {
  font-weight: bold;
  display: block;
  margin-bottom: 4px;
}

.field span {
  display: block;
  padding: 6px 10px;
  background-color: #f0f2f5;
  border-radius: 6px;
}

button {
  padding: 14px 18px;
  font-size: 1rem;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  margin: 10px 10px 0 0;
  transition: background-color 0.3s ease;
}

button.validar {
  background-color: #4caf50;
  color: white;
}

button.validar:hover {
  background-color: #45a047;
}

button.error {
  background-color: #f44336;
  color: white;
}

button.error:hover {
  background-color: #d32f2f;
}

.mensaje {
  margin-top: 20px;
  padding: 15px;
  border-radius: 8px;
  font-weight: bold;
  font-size: 1.1rem;
  text-align: center;
}

.mensaje.ok {
  background-color: #e6f4ea;
  color: #256029;
  border: 1px solid #a5d6a7;
}

.mensaje.alerta {
  background-color: #fff4e5;
  color: #a75f00;
  border: 1px solid #fbc02d;
}

.mensaje.error {
  background-color: #fcebea;
  color: #c62828;
  border: 1px solid #e57373;
}

#reader {
  margin-top: 20px;
  width: 100% !important;
  max-width: 400px;
  margin-left: auto;
  margin-right: auto;
}