<!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>