.loader {
  display: none;              /* oculto por defecto */
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 60px;
  height: 60px;
  border: 6px solid #f3f3f3;
  border-top: 6px solid #d32f2f; /* rojo */
  border-radius: 50%;
  animation: spin 1s linear infinite;
  z-index: 9999;
}

@keyframes spin {
  0% { transform: translate(-50%, -50%) rotate(0deg); }
  100% { transform: translate(-50%, -50%) rotate(360deg); }
}

.modal {
  display: none;
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background: rgba(0,0,0,0.8);
  justify-content: center;
  align-items: center;
  flex-direction: column;
  z-index: 1000;
}

.modal img {
  max-width: 90%;
  max-height: 80%;
  border-radius: 8px;
}

#cerrar {
  position: absolute;
  top: 20px;
  right: 30px;
  font-size: 32px;
  color: white;
  cursor: pointer;
}

.nav-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  font-size: 48px;
  background: none;
  border: none;
  color: white;
  cursor: pointer;
  padding: 10px;
  transition: color 0.3s;
}

#prev { left: 20px; }
#next { right: 20px; }

.nav-btn:hover {
  color: #d32f2f; /* rojo elegante al pasar el mouse */
}