text: $(document).ready(function() {
  
      $(window).scroll(function() {
  
          var height = $('.first-container').height();
          var scrollTop = $(window).scrollTop();
  
          if (scrollTop >= height - 40) {
              $('.nav-container').addClass('solid-nav');
          } else {
              $('.nav-container').removeClass('solid-nav');
          }
  
      });
  });