the rest of the page has amazing design, but there's just something about the graphs switching from dark to light that flashbangs my eyes really badly - i think it's the sudden light!

That is unintentional and a bug in the dark-mode.

For dark-mode, we rely on https://invertornot.com/ to dynamically decide whether to fade or negate/invert. (Background: https://gwern.net/invertornot ) The service uses a small NN and is not always correct, as in these cases. Sorry.

I have filed them as errors with InvertOrNot, and will manually set them to invert.