I just opened the Android Stack Exchange site to link someone to it and when I saw it I thought the page hadn't loaded properly. This is what I saw (you'll want to view full size, they're uploaded full-size):
Perhaps on some monitors it looks ok, but on both my laptop screen and my external monitor it's very hard to read. I have to physically move my head well below my monitor to read the text, especially on the smaller lines, such as the Hot Network Questions sidebar. Comments are almost unreadable.
I'm on Windows 10 Creator's Update (w/ latest updates) and Chrome 59.0.3071.115 if that makes a difference.
It'd be awesome if the font could be changed to something legible. I'm going to tag this with bug
because I think this couldn't possibly be intentional.