If you have access to the dev console I highly recommend setting the max-width of the body to 40em. The text spans all the way across the screen by default.
document.querySelector('body').style['width'] = '40em';
However, setting the max-width did not work:
document.querySelector('body').style['max-width'] = '40em';
Any idea why?
document.body.style.maxWidth = '40em'(
Will work.