.contenedor-alerta {
  position: fixed;
  top: 20px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 9999;
  width: 100%;
  max-width: 400px;
  display: flex;
  justify-content: center;
  animation: slideDown 0.3s ease;
}

.alerta-error {
  background: white;
  padding: 15px 20px;
  border-left: 5px solid #e53935;
  border-radius: 8px;
  color: #333;
  font-size: 15px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
  text-align: center;
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translate(-50%, -20px);
  }
  to {
    opacity: 1;
    transform: translate(-50%, 0);
  }
}