I have written a little userscript to do this:

https://github.com/susam/userscript/blob/main/darkhn.user.js

Additionally, I have another userscript to increase the font size:

https://github.com/susam/userscript/blob/main/bighn.user.js

Together, this is how my HN pages look:

https://susam.github.io/blob/img/misc/2026-01-19-custom-hn.p...

If there was a dark mode, it should use the `prefers-color-scheme` css media query[1] to detect user preferences.

[1] https://developer.mozilla.org/en-US/docs/Web/CSS/Reference/A...

If you can't override CSS, you aren't a hacker.