css/css-values/tree-counting/sibling-function-invalidation.html

<!DOCTYPE html>
<title>CSS Values and Units Test: Invalidation for sibling-index() and sibling-count()</title>
<link rel="help" href="https://drafts.csswg.org/css-values-5/#tree-counting">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
  #t1 {
    width: calc(10px * sibling-index());
    height: 50px;
    background: teal;
  }
</style>
<div>
  <div id="rm1"></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div id="t1"></div>
</div>
<script>
  test(() => assert_equals(t1.offsetWidth, 60), "Initially 6th sibling");
  test(() => {
    rm1.remove();
    assert_equals(t1.offsetWidth, 50);
  }, "5th sibling after removal");
</script>

<style>
  #t2 {
    width: 50px;
    height: calc(10px * sibling-count());
    background: teal;
  }
</style>
<div>
  <div id="t2"></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div id="rm2"></div>
</div>
<script>
  test(() => assert_equals(t2.offsetHeight, 60), "Initially 6 siblings");
  test(() => {
    rm2.remove();
    assert_equals(t2.offsetHeight, 50);
  }, "5 siblings after removal");
</script>