<!DOCTYPE html> <title>Layout Instability: change under overflow clipping container causing shift and overflow status change at the same time</title> <link rel="help" href="https://wicg.github.io/layout-instability/" /> <script src="/resources/testharness.js"></script> <script src="/resources/testharnessreport.js"></script> <script src="resources/util.js"></script> <div style="height: 100px"></div> <div style="overflow: auto; width: 400px; height: 400px"> <div id="resized" style="width: 600px; height: 100px; background: gray"></div> <div id="shifted" style="width: 300px; height: 100px; background: blue"></div> </div> <script> promise_test(async () => { const watcher = new ScoreWatcher; // Wait for the initial render to complete. await waitForAnimationFrames(2); resized.style.width = '200px'; resized.style.height = '200px'; const expectedScore = computeExpectedScore(300 * (100 + 100), 100); assert_equals(watcher.score, 0); await watcher.promise; assert_equals(watcher.score, expectedScore); resized.style.width = '600px'; resized.style.height = '100px'; await watcher.promise; assert_equals(watcher.score, expectedScore * 2); }, 'Change under overflow clipping container causing shift and overflow status change at the same time'); </script>