chromium/third_party/blink/web_tests/external/wpt/css/css-view-transitions/content-with-child-with-transparent-background.html

<!DOCTYPE html>
<html class=reftest-wait>
<title>View transitions: element with child with transparent background</title>
<link rel="help" href="https://drafts.csswg.org/css-view-transitions-1/">
<link rel="author" href="mailto:[email protected]">
<link rel="match" href="content-with-child-with-transparent-background-ref.html">

<script src="/common/reftest-wait.js"></script>
<style>
.shared {
  width: 50px;
  height: 50px;
  background: grey;
  position: fixed;
  top: 25px;
  left: 25px;
  view-transition-name: shared;
}
.target {
  width: 100px;
  height: 100px;
  background: rgba(0,0,0,0);
  will-change: opacity;
  position: relative;
  top: 50px;
  left: 50px;
}

.embedded {
  width: 25%;
  height: 50%;
  position: absolute;
  top: 0px;
  will-change: opacity;
}

#one{
  left: 25%;
  background: lightblue;
}
#two {
  left: 50%;
  background: lightgreen;
}

.hidden {
  width: 10px;
  height: 10px;
  background: grey;
  view-transition-name: hidden;
}

html::view-transition-group(hidden) { animation-duration: 300s; }
html::view-transition-image-pair(hidden) { animation: unset; opacity: 0; }

html::view-transition-group(shared) { animation: unset; }
html::view-transition-old(shared) { animation: unset; opacity: 1; }
html::view-transition-new(shared) { animation: unset; opacity: 0; }

</style>
<div class="shared">
  <div class="target">
    <div class="embedded" id="one"></div>
    <div class="embedded" id="two"></div>
  </div>
</div>
<div id=hidden class=hidden></div>

<script>
failIfNot(document.startViewTransition, "Missing document.startViewTransition");

async function runTest() {
  document.startViewTransition().ready.then(requestAnimationFrame(takeScreenshot));
}
onload = () => requestAnimationFrame(() => requestAnimationFrame(runTest));
</script>