title: Make element take full height of flex item container
body: <p>Is this a bug or what?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="true" data-console="false" data-babel="false">
  <div class="snippet-code snippet-currently-hidden">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>.page__header {
    background: lightgreen;
    display: flex;
    flex-direction: row;
    flex-wrap: nowrap;
    justify-content: space-between;
    align-content: stretch;
    align-items: stretch;
  }
  .page__header h1 {
    flex: 1 0;
  }
  
  .page__header button {
     order: 5;
  }
  
  .page__header div {
    align-self: left;
    order: 2;
    position: relative;
  }
  .page__header div input {
    min-width: 260px;
    padding: 0 1em;
    height: 100%;
    text-transform: uppercase;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class='page__header'&gt;
    &lt;h1&gt;title&lt;/h1&gt;
    &lt;div&gt;
      &lt;input&gt;
    &lt;/div&gt;
    &lt;button&gt;some button&lt;/button&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>Chrome, as always, refuses to cooperate. <br>Does anyone know how to force an <strong>input</strong> to take the <strong>full heigh</strong>t of its <em>flex</em> item container?</p>
  
  <p>On Firefox it obeys the <code>100%</code> height. </p>