WAVE shows that light mode is 0000ff on ffffff, for a contrast of 8.59:1.
For my tastes,
that's a bit
too much contrast,
and I'd prefer the background be very slightly off-white, around fafafa.
The example "grey text on an off-white background." is 6D6D6D on EFEFEF, for a WCAG failing contract ratio of 4.49:1.
Amusingly, the paragraph near the end of the article that begins "Truth is stranger than fiction.." is not flagged as failing.
It's 6D6D6D on FFFFFF, for a ration of 5.17:1. That passes WCAG AA but fails AAA.
https://wave.webaim.org/report#/https://catskull.net/stop-us...
Results for dark mode may vary, but I don't see a way to force it for analysis purposes.