function mostrar() {
  document.getElementById('galeriaFotos').style.display="block";
  document.getElementById('ver_off').style.display="block";
  document.getElementById('ver_on').style.display="none";
} 
function ocultar() {
  document.getElementById('galeriaFotos').style.display="none"; 
  document.getElementById('ver_off').style.display="none"; 
  document.getElementById('ver_on').style.display="block";
}