Maybe your browser's reader mode fits the bill? Firefox allows to choose serif/sans-serif fonts, font-size, line spacing and background color for example.
I hesitate to admit this, because it makes me look stupid but you are right.
I should remember to use the reader mode more often.
It is easy to forget a tool which one rarely needs, there is nothing stupid about that in my opinion :)
True :)
Well that's obvious, but really it's a shame to force reader mode on such a beautiful site. And fonts there were selected with some purpose it seems, it's just that font hinting on Windows makes them off, they probably look good on Macintosh.