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<!DOCTYPE html>
<title>Sticky positioning can cause overflow but must be accessible.</title>
<link rel="help" href="https://www.w3.org/TR/css-position-3/#sticky-pos" />
<meta name="assert" content="This test checks that a sticky positioned element
can cause overflow but must still be accessible through scrolling" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
.container {
overflow: scroll;
width: 100px;
height: 100px;
}
.box {
background-color: green;
height: 50px;
width: 50px;
}
.sticky {
position: sticky;
top: 200px; /* Forces the sticky position element below the overflow. */
}
</style>
<div id="scroller1" class="container">
<div class="sticky box"></div>
</div>
<div id="scroller2" class="container">
<div class="sticky box"></div>
</div>
<script>
test(() => {
var scroller = document.getElementById('scroller1');
var sticky = scroller.querySelector('.sticky');
var stickyOffset = sticky.offsetTop -
scroller.scrollTop - scroller.offsetTop;
assert_equals(stickyOffset, 200);
assert_equals(scroller.scrollHeight, 250);
}, 'sticky position offset should be able to cause overflow');
test(() => {
var scroller = document.getElementById('scroller2');
var sticky = scroller.querySelector('.sticky');
scroller.scrollTop = 150;
var stickyOffset = sticky.offsetTop -
scroller.scrollTop - scroller.offsetTop;
assert_equals(stickyOffset, 50);
// Scroll height should be unaffected.
assert_equals(scroller.scrollHeight, 250);
}, 'sticky position offset in overflow should be accessible');
</script>
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