Steps to replicate the issue (include links if applicable):

• see https://de.wikipedia.org/wiki/Wikipedia:Dark_Mode/Probleme#c-L%C3%B3melinde-20241008170500-Hieroglyphen in dark mode

What happens?:
the top and bottom part of the cartouche stay black because the class mw-hiero-box has a hardcoded background color of #000

What should have happened instead?:
the whole cartouche should be white in dark mode.

I would have tried to fix this myself but I'm unsure what would be a fitting token to use instead of #000. In the weird WikiHiero output, mw-hiero-box is a background that looks like a border in a multiply nested table.