Blitz - WPT: flex-basis-1.html

wpt / css / css-sizing / stretch / flex-basis-1.html

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

Subtest	Status	Message
.item 1	FAIL	assert_equals: data-expected-client-width expected 100 got 30
.item 2	FAIL	assert_equals: data-expected-client-width expected 90 got 30
.item 3	FAIL	assert_equals: data-expected-client-width expected 70 got 30
.item 4	FAIL	assert_equals: data-expected-client-width expected 50 got 30
.item 5	PASS

Enable JavaScript in test iframe

/css/css-sizing/stretch/flex-basis-1.html

<!DOCTYPE html>
<link rel="help"
  href="https://drafts.csswg.org/css-sizing-4/#stretch-fit-sizing">
<script src='/resources/testharness.js'></script>
<script src='/resources/testharnessreport.js'></script>
<script src="/resources/check-layout-th.js"></script>
<meta name="assert"
  content="stretch as a flex basis accounts for the item's margins">

<style>
  .flexbox {
    display: flex;
    width: 100px;
  }

  .item {
    flex: 0 1 stretch;
    background: lime;
  }

  .grandchild {
    width: 30px;
    height: 50px;
  }

  p {
    margin-bottom: 4px;
  }
</style>

<body onload="checkLayout('.item')">

  <p>basic:</p>
  <div class="flexbox">
    <div class="item" style="outline: 5px solid;"
      data-expected-client-width="100">
      <div class="grandchild"></div>
    </div>
  </div>

  <p>With border:</p>
  <div class="flexbox">
    <div class="item" style="border: 5px solid;"
      data-expected-client-width="90">
      <div class="grandchild"></div>
    </div>
  </div>

  <p>With border+margin:</p>
  <div class="flexbox">
    <div class="item" style="border: 5px solid; margin-right: 20px;"
      data-expected-client-width="70">
      <div class="grandchild"></div>
    </div>
  </div>

  <p>flex-basis:stretch items can still shrink:</p>
  <div class="flexbox">
    <div class="item" style="outline: 5px solid;"
      data-expected-client-width="50">
      <div class="grandchild"></div>
    </div>
    <div style="flex-basis: 100px"></div>
  </div>

  <p>column flexbox has indefinite height so flex-basis:stretch behaves as
    flex-basis:content</p>
  <div class="flexbox" style="flex-direction: column;">
    <div class="item" style="outline: 5px solid; min-height: 0px;"
      data-expected-client-height="50">
      <div class="grandchild"></div>
    </div>
  </div>