anchor.diff:    }
   
     @media (max-width: 767px) {
  -    .container-slider {
  -      display: none;
  -    }
  -
       #modal-form,
       .parafernalia-next,
       .parafernalia-back{
  
positive.code:     document.getElementById('btn-back').addEventListener('click', function(){
        clickNumber -= 1;
        size_ = size_screen*clickNumber;
        // optimizar
        if (clickNumber < 1) {
          document.getElementById('btn-back').style.display = 'none';
  
negative.code:   });
  
    document.getElementsByClassName('close')[0].addEventListener('click', function(){
  
      document.getElementById('modal-form').dataset.showup = 'false';
      setTimeout(function(){
        document.getElementById('modal-form').style.display = 'none';
  