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<!DOCTYPE html>
<title>position:sticky elements can be constrained by top and bottom exceeding container size</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 both top and bottom constraints" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
.scroller {
height: 200px;
overflow: auto;
position: relative;
}
.container {
height: 120px;
}
.padding, .sticky {
height: 50px;
}
.overflow-padding {
height: 200px;
}
.sticky {
position: sticky;
background: green;
top: -25px;
bottom: 150px;
}
</style>
<body>
<div class="scroller">
<div class="container">
<div class="padding"></div>
<div class="sticky"></div>
</div>
<div class="overflow-padding"></div>
</div>
</body>
<script>
test(() => {
const scroller = document.querySelector('.scroller');
const element = document.querySelector('.sticky');
scroller.scrollTop = 0;
assert_equals(element.offsetTop, 0);
}, 'initially the sticky box should be pushed to the top of the container');
test(() => {
const scroller = document.querySelector('.scroller');
const element = document.querySelector('.sticky');
scroller.scrollTop = 95;
assert_equals(element.offsetTop, 70);
}, 'when we scroll past the flow position the top constraint pushes it down');
</script>
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