chromium/third_party/blink/web_tests/external/wpt/css/css-backgrounds/background-clip/clip-rounded-corner.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>Filled Background with Rounded Corner</title>
<link rel="match" href="clip-rounded-corner-ref.html">
<link rel="help" href="https://drafts.csswg.org/css-backgrounds-3/#corner-clipping">
<style>
    #b {
        width: 100px;
        height: 80px;
        border: 20px blue solid;
        border-top-right-radius: 20px;
        background-color: green;
        background-clip: content-box;
    }
    #shield {
        position: absolute;
        width: 30px;
        height: 30px;
        left: 120px;
        top: 5px;
        background-color: black;
    }
</style>
<body>
    <div id="b"></div>
    <!-- Hide the curved outside border to deal with imprecise rendering. -->
    <div id="shield"></div>
</body>