font-weight: 300;

I'm 99% sure that author had designed this website on an Apple Mac with so called "font smoothing" enabled, which makes all regular fonts artificially "semi-bold". So to make a normal looking font, Mac designers use this thinner font weight and then Apple helpfully makes it kinda "normal".

https://news.ycombinator.com/item?id=23553486

The author might be formatting for and editing in dark mode. I use edge://flags/#enable-force-dark and the links are readable.

If the author stops by- the links and the comments in the code blocks were the ones that I had to use extra effort to read.

It might be worth trying to increase the contrast a bit.

The content is really great though!

The website seems to use alpha transparency for text. A grave, contrast-reducing, sin.