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<!DOCTYPE html>
<title>transforms on position:sticky elements should apply after sticking</title>
<link rel="help" href="https://www.w3.org/TR/css-position-3/#sticky-pos" />
<meta name="assert" content="This test checks that transforms on position:sticky elements are carried out on their stuck position" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/sticky-util.js"></script>
<body style="margin: 0;"></body>
<script>
test(() => {
const elements = setupStickyTest('top', 50);
elements.sticky.style.transform = 'scale(2)';
elements.scroller.scrollTop = 200;
// Transforms don't affect offsetTop, so use getBoundingClientRect.
// Scaling the sticky element by 2 means its top-y moves (1/2 * height)
// upwards, in this case placing it at the top of the viewport.
const boundingRect = elements.sticky.getBoundingClientRect();
assert_equals(boundingRect.y, elements.scroller.getBoundingClientRect().y);
}, 'Scale transforms are carried out on the stuck element position');
test(() => {
const elements = setupStickyTest('top', 50);
elements.sticky.style.transform = 'rotateX(60deg)';
elements.scroller.scrollTop = 200;
// Transforms don't affect offsetTop, so use getBoundingClientRect.
// Rotating around the x-axis essentially 'squashes' it (from the camera's
// viewpoint), in this case shifting the offset to 75 rather than 50.
const stickyElementOffset = elements.sticky.getBoundingClientRect().y -
elements.scroller.getBoundingClientRect().y;
assert_equals(stickyElementOffset, 75);
}, 'Rotate transforms are carried out on the stuck element position');
test(() => {
const elements = setupStickyTest('top', 50);
elements.sticky.style.transform = 'perspective(3px) translateZ(1px)';
elements.scroller.scrollTop = 200;
// Transforms don't affect offsetTop, so use getBoundingClientRect.
const stickyElementOffset = elements.sticky.getBoundingClientRect().y -
elements.scroller.getBoundingClientRect().y;
assert_equals(stickyElementOffset, 25);
}, 'Perspective transforms are carried out on the stuck element position');
</script>
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