css/css-flexbox/alignment/flex-align-baseline-fieldset-002.html

<!DOCTYPE html>
<link rel="help" href="https://github.com/w3c/csswg-drafts/issues/7656#issuecomment-1248617134">
<style>
.target {
  display: flex;
  position: relative;
  line-height: 0;
  writing-mode: vertical-rl;
}
.target > div {
  background: hotpink;
  font-size: 30px;
}
fieldset {
  padding: 10px;
  border: solid 10px;
  margin: 0;
  font-size: 20px;
}
span {
  display: inline-block;
  width: 1em;
  height: 1em;
  outline: solid cyan 3px;
  outline-offset: -3px;
}
</style>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/check-layout-th.js"></script>
<body onload="checkLayout('.target > *')">

<div class="target" style="align-items: first baseline;">
  <div data-offset-x="35"><span></span></div>
  <fieldset data-offset-x="0">
    <legend><span></span></legend>
    <span></span><br><span></span>
  </table>
</div>

<div class="target" style="align-items: last baseline;">
  <div data-offset-x="15"><span></span></div>
  <fieldset data-offset-x="0">
    <span></span><br><span></span>
    <legend><span></span></legend>
  </table>
</div>