chromium/third_party/blink/web_tests/external/wpt/css/css-paint-api/style-first-letter-pseudo-ref.html

<!DOCTYPE html>
<html>
<link rel="stylesheet" type="text/css" href="/fonts/ahem.css" />
<style>
div {
    color: rgb(0, 255, 0);
    line-height: 2px;
}

div::first-letter {
    color: rgb(255, 0, 0);
}
canvas{
    position: absolute;
    top: 4px;
    z-index: -1;
}
</style>
<body style="font: 10px/1 Ahem;">
<div><canvas width="10px" height="10px"></canvas>ppp</div>
<script>
document.addEventListener('DOMContentLoaded', function() {
    var canvas = document.querySelector('canvas');
    var context = canvas.getContext("2d");
    context.fillStyle = 'green';
    context.fillRect(0, 0, 10, 10);
});
</script>
</body>
</html>