sticky-scroll.css

.fixed {
  position: fixed;
  top: 0;
}

sticky-scroll.html

<div data-behavior="stick-to-top">
  content ....
</div>

sticky-scroll.js.coffee

$ ->
  el = $('[data-behavior~=stick-to-top]')

  return if el.length == 0

  top = false

  $(window).scroll ->
    top ||= el.offset().top - parseInt(el.css('marginTop'))
    windowTop = $(window).scrollTop()
    el.toggleClass('fixed', windowTop >= top)