vitrine/assets/js/main.js

function scrollDown() {
  var scroller = document.getElementById("scroller");
  var height = scroller.offsetHeight;
  scroller.scrollBy(0, height);
}

function scrollUp() {
  var scroller = document.getElementById("scroller");
  var height = scroller.offsetHeight;
  scroller.scrollBy(0, -1 * height);
}