title: Material ui contained button styling being overidden by MuiButtonBase-root
body: <p>I am using material-ui with react. I have a simple contained button using</p>
  <pre><code> &lt;Button variant='contained' color='primary'&gt; Edit&lt;/Button&gt;
  </code></pre>
  <p>However the button does not look like a contained button. As seen in this screenshot <a href="https://i.stack.imgur.com/qYXaS.png" rel="noreferrer">here</a>.</p>
  <p>Upon further investigation I found out the the .MuiButton-containedPrimary style is being overidden by the .MuiButtonBase-root styling as seen in this <a href="https://i.stack.imgur.com/4MAy1.png" rel="noreferrer">screenshot taken from chrome dev tools</a>.</p>
  <p>Please can someone let me know how to fix this?</p>