chromium/third_party/blink/web_tests/fast/scrolling/scrollbar-tickmarks-styled.html

<!DOCTYPE html>
<head>
<script src="../../resources/ahem.js"></script>
<style>
html {
    font: Ahem 10px;
    -webkit-font-smoothing: none;
}
::-webkit-scrollbar {
    width: 13px;
    height: 13px;
}
::-webkit-scrollbar-track {
    background-color:green;
}
::-webkit-scrollbar-thumb {
    background-color:rgba(128, 128, 128, 0.8);  /* Let tickmark shine through */
}
</style>
<script>
function highlight()
{
    var range = document.createRange();
    var elt = document.getElementById('elt');
    range.selectNodeContents(elt);
    if (window.internals) {
        internals.addTextMatchMarker(range, 'kActive');
    }
}
</script>
</head>
<body onload="highlight();">

<div style="height:600px"></div>
<span id="elt" style="position:absolute; top:300px">&nbsp;</span>

</body>
</html>