chromium/third_party/blink/web_tests/fragmentation/break-before-first-child.html

<!DOCTYPE html>
<script src="../resources/check-layout.js"></script>
<p>Below, there should be a green square with a border, and no red.</p>
<div id="multicol" style="columns:3; column-fill:auto; line-height:50px; height:200px;">
    <br>
    <div style="border:5px solid green; width:100px; background:red;" data-expected-width="110" data-expected-height="110">
        <div style="break-before:column; background:lime;">
            <br>
            <br>
        </div>
    </div>
</div>
<script>
    checkLayout("#multicol");
</script>