body {
  font-family: sans-serif;
  background: #f5f5f5;
  padding: 2rem;
}

h1 {
  text-align: center;
  color: #222;
}

.tarjetas {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-top: 2rem;
}

.tarjeta {
  background: white;
  padding: 1.5rem;
  border-radius: 10px;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
  text-align: center;
}