chromium/third_party/blink/web_tests/external/wpt/css/css-backgrounds/background-gradient-interpolation-001.html

<!doctype html>
<html>
<head>
<meta charset='utf-8'>
<meta name="assert" content="Use the indicated color space when interpolating colors on the gradient line.">
<link rel="stylesheet" type="text/css" href="/fonts/ahem.css" />
<link rel="help" href="https://drafts.csswg.org/css-images-4/#linear-gradients">
<link rel="help" href="https://drafts.csswg.org/css-color/#interpolation-space">
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1910153">
<link rel="mismatch" href="background-gradient-interpolation-001-notref.html">
<style>
:root {
  --space: ;
}

div {
  height: 50px;
  width: 200px;
}

.has-gradient {
  background-image: linear-gradient(
    90deg var(--space),
    yellow 30%,
    purple 95%
  );
}

.hsl {
  --space: in hsl;
}

.oklch {
  --space: in oklch;
}
</style>
</head>

<body>
  <h4>These three gradients should NOT look the same</h4>

  <p>Interpolating in sRGB (default)</p>
  <div class="has-gradient"></div>

  <p>Interpolating in HSL</p>
  <div class="has-gradient hsl"></div>

  <p>Interpolating in Oklch</p>
  <div class="has-gradient oklch"></div>
</body>
</html>