<!DOCTYPE html>
<link rel="author" title="Morten Stenshorne" href="[email protected]">
<link rel="help" href="https://www.w3.org/TR/CSS22/visudet.html#containing-block-details">
<link rel="help" href="https://www.w3.org/TR/CSS22/visuren.html#anonymous-block-level">
<style>
body { margin: 0px;}
.rel { position:relative; }
.inline-block { display:inline-block; width:100px; height:1px; }
.inline-block.large { width:200px; }
#target { position:absolute; width:100%; height:100px; background:green; }
#target-fixed { position:fixed; width:100%; height:100px; background:yellow; }
</style>
<p>There should be a green square, and a yellow rectangle below.</p>
<div style="height:200px;">
<span class="rel" id="notContainingBlockOfTarget">
<div class="large inline-block"></div>
<br>
<span id="containingBlockOfTarget" class="rel">
<div class="inline-block"></div>
<span>
<div>
<div id="target-fixed"></div>
<div id="target"></div>
</div>
</span>
<div class="inline-block"></div></span><br>
<div class="large inline-block"></div>
</span>
</div>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
test(()=> {
assert_equals(document.getElementById("target").offsetWidth,
// `offsetWidth` is not interoperable for block-in-inline.
// Use the size of ".inline-block" to avoid this.
document.querySelector("#containingBlockOfTarget .inline-block").offsetWidth);
}, "position:absolute should be sized by the right ancestor");
test(()=> {
assert_equals(document.getElementById("target-fixed").offsetWidth,
document.body.offsetWidth);
}, "position:fixed should be sized by the right ancestor");
</script>