body {
  font-family: Arial, Helvetica, sans-serif;
  background: linear-gradient(135deg, #667eea, #764ba2);
  min-height: 100vh;
  margin: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.card {
  background: #fff;
  padding: 2rem;
  border-radius: 12px;
  width: 100%;
  max-width: 420px;
  text-align: center;
  box-shadow: 0 10px 25px rgba(0,0,0,0.2);
}

button {
  background: #667eea;
  border: none;
  color: #fff;
  padding: 12px 20px;
  border-radius: 8px;
  cursor: pointer;
}

button:hover {
  background: #5a67d8;
}

#mensaje {
  margin-top: 1rem;
  font-weight: bold;
}