It's very difficult to tell, though. The gamma varies between 1.9 and 2.3 (roughly) depending on the angle at which I look at my screen. Every time I sit this will be different.

Opening the article again, it also depends where I look: when tilting my laptop back a bit, the text appears darker (even black if I tilt it far enough) but the exact shade differs: near the bottom of the page it's still greyish while the top part is indeed almost black.

Looking on my phone, it's a lot better readable than on my laptop, probably because I look at my laptop screen at an angle and my phone's colors don't change if you look from the far top or bottom.