I'm aware that you can specify styles within React classes, like this:

const MyDiv = React.createClass({
  render: function() {
    const style = {
      color: 'white',
      fontSize: 200
    };
    
    return 
 Have a good and productive day! 
;
  }
});

Should I be aiming to do all styling this way, and have no styles at all specified in my CSS file?

Or should I avoid inline styles completely?

It seems odd and messy to do a little bit of both - two places would need to be checked when tweaking styling.