The reading bar on the website is done with two really small code snippets. Yes, the CSS should be in a different file. Usually.
Include the below javascript in your <head>
:
javascript:
<script type="text/javascript">
$(document).ready(function(){
$('body').mousemove(function(event) {
$("#ruler").css('top', event.pageY - 30);
$("#ruler").css('width', $(window).innerWidth());
});
});
</script>
just after your <body>
tag, include the following html/inline css (yes, you can break it into a separate file. Probably should).
<div id="ruler" style="height: 1.4em; background-color: rgba(0,0,0,.1); position: absolute; top=-100px; z-index: -1"></div>
The z-index
keeps it from hovering over your elements and mucking up where you click. The top
just sets it so it's above the page, but you can move that any where: its going to move with the mouse after all.