css/css-grid/grid-items/grid-items-relative-positioned-containing-block-004.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Grid Layout Test: Relative Positioned Grid Items as a Containing Block of Fixed Positioned Descendant</title>
<link rel="author" title="Jo Steven Novaryo" href="mailto:steven.novaryo@gmail.com">
<link rel="help" href="https://drafts.csswg.org/css-position-3/#absolute-cb">
<link rel="help" href="https://drafts.csswg.org/css-position-3/#fixed-cb">
<link rel="help" href="https://drafts.csswg.org/css-grid/#grid-items">
<link rel="help" href="https://github.com/servo/servo/issues/34535">
<link rel="match" href="/css/reference/ref-filled-green-100px-square.xht">
<meta name="assert" content="Ensures that relative positioned grid item established as a absolute containing block correctly.">
<link rel="stylesheet" href="support/grid-items-relative-positioned-containing-block.css">

<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>

<div class="grid">
    <div class="container">
        <div class="box-fixpos red"></div>
    </div>
    <div class="box1 green"></div>
</div>