As far as I can see (I have some usable vision), the site is indistinguishable from one with no CSS. Might be a good idea to double check the link to the CSS.

Ah, I think I found the problem. The link to the stylesheet is a relative path, but it assumes that the base URL is in the root directory of the site. That's not the case for blog posts.

@matt Thank you. That's a ridiculous mistake on my part - now fixed, I believe.

Yes, it's fixed.

@matt The best way for me to detect such an issue as a screen reader user would presumably be to query font attributes (as long as I know what the defaults would be in the absence of the correct CSS). The slightly more interesting approach would be to submit a screenshot to an image-processing large language model and ask for a description of the styling.