<!DOCTYPE HTML>
<html>
<head>
    <meta charset="utf-8">
    <link rel="help" href="https://www.w3.org/TR/css-text-decor-3/#text-underline-position-property">
    <link rel="match" href="reference/text-decoration-underline-position-vertical-ref.html">
    <style>
        body { writing-mode: vertical-rl; }
        .underline { text-decoration: underline; }
        .overline { text-decoration: overline; }
    </style>
</head>
<body lang="en">
    <div class="overline" style="text-underline-position: right">サンプル</div>
    <div class="underline" style="text-underline-position: left">サンプル</div>
</body>
</html>