var bodyEle = document.querySelector('body');
var lastposition = 0;
window.addEventListener('scroll', function () {
  var currentPosition = window.scrollY || document.documentElement.scrollTop;
  if (currentPosition > 20) {
    bodyEle.classList.add('sticky-active');
  } else {
    bodyEle.classList.remove('sticky-active');
  }
  lastposition = currentPosition;
});