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chromium/third_party/blink/web_tests/fast/multicol/flexbox/flexbox.html 

<!DOCTYPE html>
<p>The word "PASS" should be seen tidily below (with large letter spacing).</p>
<div style="-webkit-columns:5; -webkit-column-gap:0; width:5em;">
    <div style="display:flex;">
        P<br>
        <br>
        A<br>
        <br>
        S<br>
        <br>
        S<br>
        <br>
    </div>
</div>