<!DOCTYPE html>
<link rel="help" href="https://html.spec.whatwg.org/C/#the-fieldset-and-legend-elements">
<!-- A test for the following paragraph:
For the purpose of calculating the used 'block-size', if the computed
'block-size' is not 'auto', the space allocated for the rendered legend's
margin box that spills out past the border, if any, is expected to be
subtracted from the 'block-size'. If the content box's block-size would be
negative, then let the content box's block-size be zero instead.
-->
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
fieldset {
  margin: 0;
  padding: 0;
  border: 2px solid black;
}
legend {
  height: 102px;
  background-color: yellow;
}
.content {
  background-color: lime;
}
</style>
<fieldset style="block-size: 200px;">
<legend>Legend</legend>
<div class="content" style="height:100%"></div>
</fieldset>

<fieldset style="block-size: 40px;">
<legend>Legend</legend>
<div class="content" style="height:100%"></div>
</fieldset>

<script>
test(() => {
  let cs = document.querySelectorAll('.content');
  assert_equals(cs[0].offsetHeight, Math.max(202 - 102, 0));
  assert_equals(cs[1].offsetHeight, Math.max(42 - 102, 0));
}, 'Test content\'s block-size');
</script>
