<!DOCTYPE html>
<meta charset="utf8">
<link rel="author" title="Vladimir Levin" href="mailto:[email protected]">
<link rel="help" href="https://drafts.csswg.org/css-scroll-anchoring/">
<meta name="assert" content="ensures that scroll anchoring does not recurse into contained offscreen elements">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
body { height: 10000px; }
#container { contain: paint; }
#overflow {
position: relative;
top: 300px;
height: 10px;
}
#anchor {
width: 10px;
height: 50px;
}
</style>
<div style="height: 800px"></div>
<div id="container" style="height: 40px">
<div id=overflow></div>
</div>
<div id="changer" style="height: 150px"></div>
<div id=anchor></div>
<script>
test(() => {
// Ensure #anchor is the only thing on screen.
// Note that #overflow would be on screen if container
// did not have layout and paint containment.
document.scrollingElement.scrollTop = 1000;
// Ensure anchor doesn't move if #changer shrinks.
const offset = anchor.getBoundingClientRect().y;
document.querySelector("#changer").style.height = "50px";
assert_equals(anchor.getBoundingClientRect().y, offset);
}, "Contain: style paint container offscreen.");
</script>
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