It's actually very problematic from an accessibility standpoint. The entire text of each post is a single pre tag which makes it almost impossible to use with a screen reader. This is exactly why there were complaints about fancy style on websites; it often ruins the structural markup of a page.

And has terrible contrast on the main page content's text making it hard to read if you have poor eyesight, poor light conditions or a poor monitor.

This would probably fail a basic Universal Accessibility test based on that alone.

I don't like low-contrast sites, but on my monitor that one is stark black-and-white. In fact there are no CSS rules for the color, and the font stack is "Inconsolata, Courier" so I don't know what the issue could be.

It's black and white on my MBP (Chrome). Maybe your browser is the one messing it up.

Not seeing what you're describing either.