title: Flex / Grid layouts not working on button or fieldset elements
body: <p>I'm trying to center inner elements of a <code>&lt;button&gt;</code>-tag with flexbox's <code>justify-content: center</code>. But Safari does not center them. I can apply the same style to any other tags and it works as intended (see the <code>&lt;p&gt;</code>-tag). Only the button is left-aligned.</p>
  
  <p>Try Firefox or Chrome and you can see the difference.</p>
  
  <p>Is there any user agent style I have to overwrite? Or any other solution to this problem?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>div {
    display: flex;
    flex-direction: column;
    width: 100%;
  }
  button, p {
    display: flex;
    flex-direction: row;
    justify-content: center;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div&gt;
    &lt;button&gt;
      &lt;span&gt;Test&lt;/span&gt;
      &lt;span&gt;Test&lt;/span&gt;
    &lt;/button&gt;
    &lt;p&gt;
      &lt;span&gt;Test&lt;/span&gt;
      &lt;span&gt;Test&lt;/span&gt;
    &lt;/p&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>And a jsfiddle:
  <a href="http://jsfiddle.net/z3sfwtn2/2/" rel="noreferrer">http://jsfiddle.net/z3sfwtn2/2/</a></p>