[johndcook]

I believe the SVG file has a transparent background, but the img tag has style="background-color:white". Some browsers honor the background-color setting and show a white background behind the equations, even in dark mode. Some do not, and so the equations appear as black-on-black.

It would be better if I altered the SVG image itself to set the background color, but I don't know how to do that. Suggestions are welcome.

[layer8]

Displaying black on white in dark mode is still bad. In principle, CSS invert() should be able to do the trick for SVGs. You’d have to test it on all relevant browsers though.

[xigoi]

Not even that, you should just use currentColor rather than black in SVGs.