<!DOCTYPE html>
<title>position:sticky elements should not affect the flow position of other elements</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 do not affect the flow position of other elements" />

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<style>
.scroller {
  position: relative;
  height: 200px;
  width: 100px;
  overflow: scroll;
}

#sticky {
  background-color: green;
  position: sticky;
  top: 150px;
}

#before {
  background-color: fuchsia;
}

#after {
  background-color: orange;
}

.box {
  height: 50px;
  width: 50px;
}

.padding {
  height: 500px;
}
</style>

<div class="scroller">
  <div id="before" class="box"></div>
  <div id="sticky" class="box"></div>
  <div id="after" class="box"></div>
  <div class="padding"></div>
</div>

<script>
test(() => {
  // The sticky element is pushed to be stuck 150 pixels from the top.
  assert_equals(sticky.offsetTop, 150);

  // Neither 'before' or 'after' should be affected by the change in the sticky
  // element's location.
  assert_equals(before.offsetTop, 0);
  assert_equals(after.offsetTop, before.clientHeight + sticky.clientHeight);
}, 'sticky offset should not affect the position of other elements.');
</script>