The text reflows to whatever margins you like. I let people choose the margins, instead of forcing people to use specific margins that I forced on them. If you resize your window, you can get any size you want.

In Firefox you can click on the reader view icon (top right in the URL bar). In Chrome, you can start the browser with the command line option `--enable-dom-distiller`, which will give you a new menu entry "Distill page" that has the same effect.