<script type=“text/javascript”>

window.onscroll = function() {myScrollIndicator()};
function myScrollIndicator() {
  var winScroll = document.body.scrollTop || document.documentElement.scrollTop;
  var height = document.documentElement.scrollHeight - document.documentElement.clientHeight;
  var scrolled = (winScroll / height) * 100;
  document.getElementById("myBar").style.width = scrolled + "%";
}

</script>

<div class=“header”>

<div class="progress-container">
  <div class="progress-bar" id="myBar"></div>
</div>

</div>