Responsive highcharts with flexbox

Question

I am trying to have multiple highcharts share horizontal space and be responsive using flexbox.

http://jsfiddle.net/4GFyj/67/

It works on its own (without charts) so the problem must be in charts?

#wrapper {
  display: flex;
}

.inner {
  flex-basis: 100%;
}

.container {
  border: 1px solid #333;
}

<div id="wrapper">
  <div class="inner">
    <div class="container">1</div>
  </div>
  <div class="inner">
    <div class="container">2</div>
  </div>
</div>