forced-colors-mode/forced-colors-mode-17-ref.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>Forced colors mode - text decoration and emphasis color reference.</title>
<style>
  p {
    forced-color-adjust: none;
    text-decoration: underline;
    text-decoration-color: CanvasText;
    text-emphasis: '*' CanvasText;
    -webkit-text-emphasis: '*' CanvasText;
  }
</style>
<body>
  <p>
    The text decoration and emphasis color for this text should have a
    CanvasText color in forced colors mode.
  </p>
</body>