User blog comment:Rupert Giles/Layout Changes: Breakpoints and Typography/@comment-24703334-20150522073547/@comment-24703334-20150523085839

You're right, I forgot to mention this: When editing the preview doesn't show how really the page will be in final. (got similar results as your screenshots with wrong font size) The preview system is broken too.

How can you have good practice if what you see is not what you get? And it's editors fault if viewers got poor readibility?

Bad joke.