text: export function getScrollTop() {
      let de = document.documentElement,
          body = document.body;
      let st = 0;
      if (window.pageYOffset) {
          st = window.pageYOffset;
      } else if (de && de.scrollTop) {
          st = de.scrollTop;
      } else if (body.scrollTop) {
          st = body.scrollTop;
      }
      return st;
  }