<!DOCTYPE html>
<title>anchor-name is a tree scoped reference</title>
<link rel="help" href="https://drafts.csswg.org/css-anchor-1/#target-anchor-element">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
  body { margin-top: 0; }
  #anchor {
    anchor-name: --anchor;
  }
  #filler {
    height: 100px;
  }
  #anchored {
    position: absolute;
    top: anchor(--anchor top);
  }
</style>
<div id="host"></div>
<div id="filler"></div>
<div id="anchor"></div>
<div id="anchored"></div>
<script>
  const host_root = host.attachShadow({mode:"open"});
  host_root.innerHTML = `
    <style>
      div { anchor-name: --anchor; }
    </style>
    <div></div>
  `;

  test(() => {
    assert_equals(anchored.offsetTop, 100, "#anchored is positioned against #anchor");
  }, "anchor-name should not leak out of a shadow tree");
</script>

<div id="anchor_host" style="anchor-name: --anchor-host"></div>
<script>
  const anchor_host_root = anchor_host.attachShadow({mode:"open"});
  anchor_host_root.innerHTML = `
    <style>
      div {
        position: absolute;
        left: anchor(--anchor-host left, 37px);
      }
    </style>
    <div id="anchored"></div>
  `;

  test(() => {
    assert_equals(anchor_host_root.querySelector("#anchored").offsetLeft, 37, "#anchored is positioned using fallback");
  }, "anchor() in shadow tree should not match host anchor-name");
</script>
