selectOnScroll = () => {
    const position = core.scrollTop()
    let activeSet = false
    for (let index = (links.length-1); index >= 0; index--) {
      const link = links[index]
      link.link.removeClass('is-active')
      if ((position + OFFSET) >= link.offset) {
        if (!activeSet) {
          link.link.addClass('is-active')
          activeSet = true
        } else {
          link.link.addClass('is-past')
        }
      } else {
        link.link.removeClass('is-past')
      }
    }
  }
@type  {Array<{link: El, offset: number}>}