To be honest that website looks very bad to me. Fonts are too thin and that makes the text quite difficult to read. Much more than e.g. HN. And that's in my desktop PC, in mobile I went directly to close the tab.

(Update) The "high contrast" CSS style they provide is more readable, but I'm sure it should be possible to create a dark style where readability doesn't suffer that much. That font is just not the best choice.