[filter-effects-1] Spec respects dark mode, but math is still rendered in black, rendering massive chunks of the spec unreadable

[dead-claudia]

Example: https://drafts.fxtf.org/filter-effects/#element-attrdef-fecolormatrix-values

Dark mode:

Light mode:

Obviously using Brave as per the private tab color, but it's very unlikely to be Brave-specific.

Fortunately, switching between light and dark mode in the browser settings immediately reflects for me, but it makes the specs a lot harder to read ordinarily and is probably a CSS oversight. Also, this isn't specific to that spec, just that's one spec where I have those issues.