title: How can I change the focused color of a TextField?
body: <p>I am making use of Material-UI React library and I need to change the border color of a <code>TextField</code> when it is clicked or focused as the case maybe.</p>
  <p>Here is what I have tried:</p>
  <pre><code>const useFormFieldStyles = makeStyles((theme) =&gt; ({
    input: {
      borderWidth: '1px',
      fontWeight: 'bold',
      '&amp; .MuiOutlinedInput-input:focused': {
        borderColor: 'green',
      }
    }
  }));
  </code></pre>
  <p>Yet, the <code>borderColor</code> is still blue despite all my efforts.</p>
  <p>How can I make this work?</p>