nested-floats-expand-formatting-context.html

<!DOCTYPE html>
<style>
#section {
    overflow: hidden;
    width: 200px;
}

#article {
    background: black;
    height: 100px;
}

.item {
    height: 100px;
    background: black;
    padding: 50px;
}

.float {
    width: 150px;
    height: 140px;
    float: left;
    background: black;
}
</style>
<html>
<div id="section">
    <div id="article">
        <div>
            <div class="item">
                <div class="float"></div>
            </div>
        </div>
    </div>
</div>
<p>crbug.com/477076: If a nested float doesn't overhang its container the block setting the formatting context should still expand to include it if necessary. </p>

chromium/third_party/blink/web_tests/fast/block/float/nested-floats-expand-formatting-context.html