[mrep]

I prefer it straight black which this minimal CSS does (Screenshot: https://imgur.com/a/2lcy1Ga)

  :root,
  html { 
     background-color: white;
     filter: invert(100%);
  }
   
  * { 
     background-color: inherit;
  }

[sfvisser]

Nice. You can also add a `hue-rotate(180deg)` to somewhat preserve colors and add `img` to invert images back to normal again.

I have this as a bookmark and work well in many cases.