clip-negative-bottom-margin.html

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This test has a WPT meta file that expects 1 subtest issues.
This WPT test may be referenced by the following Test IDs:
- /layout-instability/clip-negative-bottom-margin.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<title>Layout Instability: clip with negative bottom margin</title>

<link rel="help" href="https://wicg.github.io/layout-instability/" />

<style>

#scroller { overflow: scroll; width: 200px; height: 500px; }

#space { height: 1000px; margin-bottom: -500px; }

#j { width: 150px; height: 150px; background: yellow; }

</style>

<div id='scroller'>

  <div id='space'></div>

  <div id='j'></div>

</div>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script src="resources/util.js"></script>

<script>

promise_test(async () => {

  const watcher = new ScoreWatcher;

  // Wait for the initial render to complete.

  await waitForAnimationFrames(2);

  // Increase j's top margin by 100px. Since j is fully clipped by the scroller,

  // this should not generate a shift.

  document.querySelector("#j").style.marginTop = "100px";

  await waitForAnimationFrames(3);

  assert_equals(watcher.score, 0);

}, "Clip with negative bottom margin.");

</script>