The site definitely has CSS, just not a lot of it.
Raw HTML definitely looks much uglier, sadly (“Reader mode” in most browsers makes websites without CSS easily readable, though!).
pretty much all HTML, with only the bare minimum CSS to make it somewhat responsive.
I guess if you want one tiny piece of feedback, based on the above site:
>A little less contrast
>Black on white? How often do you see that kind of contrast in real life? Tone it down a bit, asshole. I would've even made this site's background a nice #EEEEEE if I wasn't so focused on keeping declarations to a lean 7 fucking lines.
I agree with the advice, but I've definitely seen many a heated debate over raw black on raw white amongst designers. So take with a grain of salt and a handful of personal preference.
In books. If you have really high-end hardware where you have enough contrast to be painful, turn down your contrast setting. On regular-person devices, grey-on-grey is needlessly hard to read, and there's no way to turn the contrast up without introducing clipping.