<!DOCTYPE html>
<title>position:sticky elements should respect the bottom constraint</title>
<link rel="help" href="https://www.w3.org/TR/css-position-3/#sticky-pos" />
<meta name="assert" content="This test checks that position:sticky elements obey their bottom anchor after scrolling" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="../resources/sticky-util.js"></script>
<body></body>
<script>
test(() => {
const elements = setupStickyTest('bottom', 25);
elements.scroller.scrollTop = 300;
const nonStickyTopY = elements.container.offsetTop +
elements.filler.clientHeight;
assert_equals(elements.sticky.offsetTop, nonStickyTopY);
}, 'before reaching the sticking point the sticky box should not be offset');
test(() => {
const elements = setupStickyTest('bottom', 25);
elements.scroller.scrollTop = 100;
const nonStickyTopY = elements.container.offsetTop +
elements.filler.clientHeight;
const nonStickyBottomY = nonStickyTopY + elements.sticky.clientHeight;
const targetBottomY = elements.scroller.clientHeight +
elements.scroller.scrollTop - 25;
const stickyOffset = nonStickyBottomY - targetBottomY;
assert_equals(elements.sticky.offsetTop, nonStickyTopY - stickyOffset);
}, 'after reaching the sticking point the sticky box should be offset');
test(() => {
const elements = setupStickyTest('bottom', 25);
elements.scroller.scrollTop = 0;
assert_equals(elements.sticky.offsetTop, elements.container.offsetTop);
}, 'the sticky box should not be pushed outside its containing block');
</script>