x
 
<html>
<head>
<script type="text/javascript">
function setScrollbarHighlightColor()
{
document.body.style.scrollbarHighlightColor="purple";
}
</script>
</head> 
<body>
<input type="button" onclick="setScrollbarHighlightColor()" value="Set ScrollbarHighlightColor" />
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
<p>An example paragraph</p>
</body>
</html>