The site is messed up in Safari (at least on my machine).
The website seems to work fine in GNOME Web (tested on Epiphany 3.36.4 and Epiphany 42.2, which both use WebKit 605.1.15). I guess it must be a Safari only problem? Consider reporting your problems to Apple if the website doesn't work right on their browser, as the open source version of the underlying engine renders it fine.
Sorry, I'm not familiar with reddit leaking.