title: How to change MUI Radio button checked color?
body: <p>The <code>color</code> prop can only take three values (default, primary, secondary) but what if I want my radio to be green for example ? </p>
  
  <p>So I tried overriding with <code>classes</code> prop like so :</p>
  
  <pre class="lang-js prettyprint-override"><code>const styles = theme =&gt; ({
    radio: {
      colorPrimary: {
      '&amp;$checked': {
        color: 'blue'
      }
    },
    checked: {},
    } 
  })
  </code></pre>
  
  <p>And then inside the component :</p>
  
  <pre><code>&lt;FormControlLabel
     classes={{root: classes.formControlLabelRoot, label: classes.formControlLabel}}
     value="week"
     control={&lt;Radio disableRipple classes={{colorPrimary: classes.radio}} /&gt;}
     label="Every week (Monday at 12:00)"
  /&gt;
  </code></pre>
  
  <p>But this is not working.  </p>