div class="flexbox" style="-webkit-justify-content: space-around">
  <div data-expected-width="800" data-offset-x="-100" style="width: 800px;"></div>
</div>

<!-- Make sure we don't crash with no children. -->
<div class="flexbox" style="-webkit-justify-content: space-around"></div>

<!-- margin:auto applies before justify-content. -->
<div class="flexbox" style="-webkit-justify-content: flex-end">
  <div data-expected-width="100" data-offset-x="0" style="width: 100px;"></div>
  <div data-expected-width="10