FWIW, this is much more readable if the CSS justify rule is disabled.
"Many people with cognitive disabilities have a great deal of trouble with blocks of text that are justified (aligned to both the left and the right margins). The spaces between words create "rivers of white" running down the page, which can make the text difficult for some people to read. This failure describes situations where this confusing text layout occurs. The best way to avoid this problem is not to create text layout that is fully justified (aligned to both the left and the right margins)."
Sure, CSS is on-topic on HN, just like this article about cryptography is on-topic. However, commenting on the HTTPS certificate particulars of a site with a blog post about CSS would be similarly off-topic in a discussion about that blog post :)
(Personally, I am on the fence about the appropriateness of the comment, but I hope I have shed some light on why others would down-vote it)