Edit in JSFiddle

// UNCOMMENT THIS AT SHOP
//require(['jquery', '$ready!'], function ($) {

// Ylänavigaation lukitus
if ($('div.NavBarTop').length) {
  var stickyNavTop = $('.NavBarTop').offset().top;

  var stickyNav = function() {
    var scrollTop = $(window).scrollTop();

    if (scrollTop > stickyNavTop) {
      $('.NavBarTop').addClass('sticky');
    } else {
      $('.NavBarTop').removeClass('sticky');
    }
  };

  stickyNav();

  $(window).scroll(function() {
    stickyNav();
  });
}

// UNCOMMENT THIS AT SHOP
//});
.sticky {
  position: fixed !important;
  top: 0;
  width: 100%;
  z-index: 500;
}

.sticky .NavBarTop {
  margin: auto;
}

/* Jos käytössä North-teeman valikko */

.menu ul.show-on-mobile {
  height: 100vh;
  overflow: scroll;
}

/* Jos normaali megamenu */

.ep-megamenu-container {
  overflow-y: scroll;
  max-height: 1950px !important;
  height: 450px;
}