Yeah, it looks like the font is scaled slightly wrong along the x-axis, so that the displayed pixels don't quite line up with screen pixels. Specifically, the text is rendered about 0.5% too narrow, causing a moire-type pattern that repeats about every 200 pixels.
Adding this custom CSS rule seems to fix it for me:
Same here, I think it's caused by the font it's using (BitGeneva12 [1], which obviously is a geneva [2] clone but I can't find where it (the font) is from. Maybe the author created it themselves?).
This seems to be because Firefox has no way to disable text antialiasing (whereas Safari and Chrome support -webkit-font-smoothing), so Firefox is trying to antialias a pixel font which just looks weird
Adding this custom CSS rule seems to fix it for me: