I don't know if I feel more or less betrayed by the fact that the HTML seems to be more or less bespoke and a screen reader would have no problem with the page, but all of these choices feel all the more intentional.
However, the contrast is WCAG AA-conformant (except for the links that aren't in a black box, which aren't important links, as I went out of my way to confirm as I wrote the post). The page is actually pretty accessible.
Accessibility is important to me, as many people I've known in my life have been disabled, but so are silly aesthetic choices.
It was intentional, but it also was well-intentioned. That's why it's readable in more or less every web browser, regardless of whether it supports the one line of CSS I'm using, and accessible to screen readers (although I didn't throw in any elements specifically for them, the page is written simply enough that it should work, intentionally).
Yellow as background can work well, but this is not the way.