no-squashing-into-fixed-position-that-clips.html

<!DOCTYPE html>
<style>
.notsquashedelement {
  top: 0;
  right: 0;
  left: 0;
  z-index: 1000;
  height: 60px;
  background-color: green;
  position: fixed;
}

.fixedpos {
  position: fixed;
  top: 50px;
  right: 0;
  left: 0;
  bottom: 0;
  overflow-y: auto;
  background-color: lightblue;
}

.compositedlayer {
  position: fixed;
  top: 40px;
  left: 50%;
  width: 24px;
  height: 100px;
  background: lightgray;
  will-change: transform;
}
</style>
<div class="notsquashedelement"></div>
<div class="fixedpos">
  <div class="compositedlayer"></div>
</div>
<pre id="output"></pre>
<script>
// Tests that not squashing into an element with a different clip works correctly with fixed-position layers.
if (window.testRunner)
    testRunner.dumpAsText();

if (window.internals)
    output.textContent = internals.layerTreeAsText(document);
</script>

chromium/third_party/blink/web_tests/compositing/squashing/no-squashing-into-fixed-position-that-clips.html