Blitz - WPT: block-height-004.html

wpt / css / css-sizing / stretch / block-height-004.html

Data from commit:
708eb61 WPT runner: support mismatch reftests and multiple rel=match links (#665) (2026-08-09)

Subtest	Status	Message
.inner 1	FAIL	assert_equals: data-expected-height expected 100 got 6
.inner 2	FAIL	assert_equals: data-expected-height expected 100 got 6
.inner 3	FAIL	assert_equals: data-expected-height expected 100 got 6
.inner 4	FAIL	assert_equals: data-expected-height expected 100 got 6
.inner 5	FAIL	assert_equals: data-expected-height expected 100 got 6
.inner 6	FAIL	assert_equals: data-expected-height expected 90 got 6
.inner 7	FAIL	assert_equals: data-expected-height expected 90 got 6
.inner 8	FAIL	assert_equals: data-expected-height expected 80 got 6

Enable JavaScript in test iframe

/css/css-sizing/stretch/block-height-004.html

<!DOCTYPE html>
<link rel="help"
  href="https://drafts.csswg.org/css-sizing-4/#stretch-fit-sizing">
<link rel="help" href="https://github.com/w3c/csswg-drafts/issues/11044">
<script src='/resources/testharness.js'></script>
<script src='/resources/testharnessreport.js'></script>
<script src="/resources/check-layout-th.js"></script>
<meta name="assert"
  content="margins of the stretched element are accounted for correctly in a variety of scenarios, mostly around siblings">

<style>
  .outer {
    width: 100px;
    height: 100px;
    outline: solid;
    position: relative;
  }

  .inner {
    height: stretch;
    margin: 10px;
  }
</style>

<h2>These tests assert the behavior described at
  https://github.com/w3c/csswg-drafts/issues/11044#issuecomment-2599101601
</h2>

<p>Basic case: treat margins as 0.</p>
<div class="outer">
  <div class="inner" style="border: solid magenta;" data-expected-height="100"
    data-offset-y="0">
  </div>
</div>

<p>
  When resolving stretch treat both block margins as 0 because the parent is
  not a BFC and has no top or bottom content edge (i.e. border + padding = 0).
  <br>But cyan's margins will not actually collapse through its IFC-siblings so
  there is overflow:
</p>
<div class="outer">
  <div style="overflow: hidden"></div>
  <div class="inner" style="border: solid cyan;" data-expected-height="100"
    data-offset-y="10">
  </div>
  <div style="overflow: hidden"></div>
</div>

<div class="outer">
  <div></div>
  <div class="inner" style="border: solid blue;" data-expected-height="100"
    data-offset-y="0">
  </div>
  <div></div>
</div>

<div class="outer">
  <div></div>
  <div class="inner" style="border: solid purple;" data-expected-height="100"
    data-offset-y="0">
  </div>
</div>

<div class="outer">
  <div class="inner" style="border: solid lime;" data-expected-height="100"
    data-offset-y="0">
  </div>
  <div></div>
</div>

<p>Parent has non-zero bottom border, so only top margin is treated as 0:</p>
<div class="outer" style="border-bottom: 5px dashed blue;">
  <div class="inner" style="border: solid brown;" data-expected-height="90"
    data-offset-y="0">
  </div>
</div>

<p>Parent has non-zero top padding so only bottom margin is treated as 0:</p>
<div class="outer" style="padding-top: 5px;">
  <div class="inner" style="border: solid darkgreen;" data-expected-height="90"
    data-offset-y="15"> <!-- 15 = 10px top margin + parent's padding-->
  </div>
</div>

<p>Account for the margins when parent establishes a BFC.</p>
<div class="outer" style="display: flow-root;">
  <div class="inner" style="border: solid orange;" data-expected-height="80"
    data-offset-y="10">
  </div>
  <div></div>
</div>

<script>checkLayout(".inner");</script>