Firefox also defaults to HTTPS by default nowadays. Lots of content blockers block third party content too. Regardless, if literally anything goes wrong with the third party dependency that the article's contrast depends on, the best case scenario here is that the text falls back on the body's background.
Interestingly, the author also appears to control yu8.us
Breaking one's own content by https-ing one site but not another is a great example of why to not prop up a website's basic legibility on a third party dependency, even if it's one you own and control.
Interestingly, the author also appears to control yu8.us
Breaking one's own content by https-ing one site but not another is a great example of why to not prop up a website's basic legibility on a third party dependency, even if it's one you own and control.