Has opposite effect on some websites
for example: github is bright in night mode and dark in day mode.

Besides that, I don't fancy the method of inverting colors
especially as there are other addons on the site that achieve the same effect via modifying .css

If you would split the RGB string and invert each piece seperately ( To preserve hue instead of messing it up ) And fix the issue with sites.
This addon would be a must have. Cheers