s="flexbox column" style="height: 400px">
    <div></div><div></div><div></div>
</div>

<h3>flex-flow: column, red box has height: auto</h3>
<div class="flexbox column">
    <div></div><div></div><div></div>
</div>

<h3>flex-box has box-sizing: border-box and flex-wrap: wrap;</h3>
<div class="flexbox column wrap" style="box-sizing: border-box; border: 2px solid lightblue; padding: 3px; height: 200px; width: 100px; position: relative" data-expected-width=100 data-expected-height=200>
    <div data-offset-x=3