chromium/third_party/blink/web_tests/wpt_internal/css/css-size-adjust/text-size-adjust-affects-font-size-with-narrow-page.html

<!DOCTYPE html>
<meta content="width=100" name="viewport">
<meta name="assert" content="text-size-adjust should affect font-size, even if a narrow viewport is used.">
<link rel="help" href="https://drafts.csswg.org/css-size-adjust/#propdef-text-size-adjust">
<script src='/resources/testharness.js'></script>
<script src='/resources/testharnessreport.js'></script>
<script>
  function runTest() {
    // This should not be needed but is required to work around a bug in
    // Chrome's old autosizer due to computed style being updated during layout.
    // TODO(pdr): Remove this when b/340389272 launches.
    const forceLayout = document.body.offsetHeight;

    test(() => {
      const fontSize = getComputedStyle(textSizeAdjust75)['font-size'];
      assert_equals(fontSize, '12px');
    }, 'Font-size on element with text-size-adjust: 75%');

    test(() => {
      const fontSize = getComputedStyle(textSizeAdjust100)['font-size'];
      assert_equals(fontSize, '16px');
    }, 'Font-size on element with text-size-adjust: 100%');

    test(() => {
      const fontSize = getComputedStyle(textSizeAdjust125)['font-size'];
      assert_equals(fontSize, '20px');
    }, 'Font-size on element with text-size-adjust: 125%');
  }
</script>
<body onload="runTest()">
  <div id="textSizeAdjust75" style="text-size-adjust: 75%;">Hello world</div>
  <div id="textSizeAdjust100" style="text-size-adjust: 100%;">Hello world</div>
  <div id="textSizeAdjust125" style="text-size-adjust: 125%;">Hello world</div>
</body>