rendering of latex equation in dark mode

[Remi-Gau]

We encountered a small issue on our doc where latex equation were hard to view in dark mode:

nilearn/nilearn#5210

also it often felt like latex images (img with a 'math' class) were always a bit higher than the rest of the text when inlined

the way we will probably fix this is by adding this to our custom css:

https://github.com/nilearn/nilearn/pull/5213/files

/* Latex images
latex equation are inserted as images but are bit higher
than the rest of the text and do not play nice with dark mode
*/

img.math {
  transform: translateY(2px);
}

/* Light Mode */
[data-theme="light"] img.math {
  filter: invert(0);
}

/* Dark Mode */
[data-theme="dark"] img.math {
  filter: invert(1);
}

/* Auto Mode - Uses System Preference */
[data-theme="auto"] img.math {
  filter: invert(0);
}

@media (prefers-color-scheme: dark) {
  [data-theme="auto"] img.math {
    filter: invert(1);
  }
}

if there is a better way, feel free to chime in