wpt / css / css-flexbox / percent-height-flex-items-cross-sizes-with-mutations.html

Status: PASS | Duration: 57ms | Subtests: 21/21 | Open test on wpt.live | wpt.fyi

TestTest SourceSubtests (21/21)

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a50cb89 wpt: run reference-named files which are themselves tests (#836) (2026-09-03)

SubtestStatusMessage
percent-height-flex-items-cross-sizes-with-mutationsPASS
percent-height-flex-items-cross-sizes-with-mutations 1PASS
percent-height-flex-items-cross-sizes-with-mutations 2PASS
percent-height-flex-items-cross-sizes-with-mutations 3PASS
percent-height-flex-items-cross-sizes-with-mutations 4PASS
percent-height-flex-items-cross-sizes-with-mutations 5PASS
percent-height-flex-items-cross-sizes-with-mutations 6PASS
percent-height-flex-items-cross-sizes-with-mutations 7PASS
percent-height-flex-items-cross-sizes-with-mutations 8PASS
percent-height-flex-items-cross-sizes-with-mutations 9PASS
percent-height-flex-items-cross-sizes-with-mutations 10PASS
percent-height-flex-items-cross-sizes-with-mutations 11PASS
percent-height-flex-items-cross-sizes-with-mutations 12PASS
percent-height-flex-items-cross-sizes-with-mutations 13PASS
percent-height-flex-items-cross-sizes-with-mutations 14PASS
percent-height-flex-items-cross-sizes-with-mutations 15PASS
percent-height-flex-items-cross-sizes-with-mutations 16PASS
percent-height-flex-items-cross-sizes-with-mutations 17PASS
percent-height-flex-items-cross-sizes-with-mutations 18PASS
percent-height-flex-items-cross-sizes-with-mutations 19PASS
percent-height-flex-items-cross-sizes-with-mutations 20PASS

/css/css-flexbox/percent-height-flex-items-cross-sizes-with-mutations.html

<!DOCTYPE html>
<html>
<head>
<link rel="author" title="Sammy Gill" href="mailto:sammy.gill@apple.com">
<link rel="help" href="https://drafts.csswg.org/css-flexbox-1/#layout-algorithm">
<link rel="stylesheet" type="text/css" href="/fonts/ahem.css">
<meta name="assert" content="Tests that the cross size of flexboxes and flex items with % height are computed correctly with various mutations.">
<style>
.flexbox {
  display: flex;
  font: 10px/1 Ahem;
  outline: 1px solid black;
}
.grid {
  display: grid;
  outline: 1px solid magenta;
}
.flexbox > div {
  width: min-content;
  outline: 1px solid blue;
}
.percent-height {
  min-height: 100%;
}
.fixed-height {
  height: 100px;
}
.align-start {
  align-items: start;
}
</style>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
function mutateContent() {
  document.querySelectorAll("#one, #two, #three").forEach((element) => {
    element.innerHTML += " a";
  });

  document.querySelector("#four").style.width = "auto";
  document.querySelector("#five").style.height = "auto";
  document.querySelector("#six").style.height = "100px";

  document.querySelectorAll("#seven, #eight").forEach((element) => {
    element.style.alignItems = "start";
  });
}
</script>
</head>
<body>

<!-- Non-percent height flex item is mutated and percent height flex item should be
     stretched up. -->
<div class="flexbox test" data-expected-height="40">
  <div id="one" class="test" data-expected-height="40">a a a</div>
  <div class="percent-height test" data-expected-height="40">a</div>
</div>

<!-- Non-percent height flex item content is mutated and should be stretched to percent
     height flex item's size. -->
<div class="flexbox test" data-expected-height="40">
  <div id="two" class="min-content percent-height test" data-expected-height="40">a a a</div>
  <div class="test" data-expected-height="40">a</div>
</div>

<!-- Percent height flex item content is mutated and increased flexbox's cross axis size. -->
<div class="flexbox test" data-expected-height="30">
  <div class="min-content percent-height test" data-expected-height="30">a a a</div>
  <div id="three" data-expected-height="30">a</div>
</div>

<!-- Percent height flex item's main axis size changes from min-content to auto which
     should result in different cross size. -->
<div class="flexbox test" data-expected-height="10">
  <div class="min-content percent-height test" id="four" data-expected-height="10">a a a</div>
</div>

<!-- Flexbox with align-items: flex-start changes from definite to indefinite cross size
     which results in different hypothetical cross size for flex item.-->
<div class="flexbox fixed-height align-start test" id="five" data-expected-height="30">
  <div class="min-content percent-height test" data-expected-height="30">a a a</div>
  <div class="test" data-expected-height="10">a</div>
</div>


<!-- Flexbox with align-items: flex-start changes from indefinite to definite cross size
     which results in different hypothetical cross size for the flex item. -->
<div class="flexbox align-start test" id="six" data-expected-height="100">
  <div class="min-content percent-height test" data-expected-height="100">a a a</div>
</div>

<!-- Outer flexbox goes from stretching its content to no longer stretching with a
     definite cross size. The inner flexbox is no longer stretching which affects the
     hypothetical cross axis size of its flex item. -->
<div class="flexbox fixed-height test" id="seven" data-expected-height="100"">
  <div class="flexbox align-start test" data-expected-height="30">
    <div class="min-content percent-height test" data-expected-height="30">a a a</div>
  </div>
</div>

<!-- Grid goes from stretching its content to no longer stretching with a definite cross
     size. The flexbox is no longer stretching which affects the hypothetical cross axis
     size of tis flex item.-->
<div class="grid fixed-height test" id="eight" data-expected-height="100">
  <div class="flexbox align-start test" data-expected-height="30">
    <div class="min-content percent-height test" data-expected-height="30">a a a</div>
  </div>
</div>

</body>
<script>
document.body.offsetHeight;
mutateContent();
document.body.offsetHeight;

let tests = document.querySelectorAll(".test");
tests.forEach((element) => {
  test(function() {
    let expectedHeight = element.getAttribute("data-expected-height");
    assert_equals(element.offsetHeight, Number(expectedHeight), "height");
  });
});
</script>
</html>