Евгений Щербаков

.attr('fill', function(d,i){
                  if ( i > 0 ) {
                        return colors(d);
                  } else {
                        return 'red';
                  }
            })

import { makeStyles } from "@material-ui/core/styles";
import Switch from "@material-ui/core/Switch";

const useStyles = makeStyles({
  classForDisabled: {
    // ...your css...
  }
});

export default function App() {
  const styles = useStyles();

  return (
    <div className="App">
      <Switch classes={{ disabled: styles.classForDisabled }} disabled={true} />
    </div>
  );
}

a {
   padding: 10px;
   border-bottom: 1px solid transparent;
   text-decoration: none;
}

a:hover {
   border-bottom: 1px solid #fff;
   text-decoration: none;
}