Dark mode everywhere for Tampermonkey or Greasemonkey

darkmode.js

// ==UserScript==
// @name Dark HN
// @match https://news.ycombinator.com/*
// @version      0.1
// @description  Simple dark mode
// @author       You
// @grant        none
// @run-at document-start
// ==/UserScript==

window.addEventListener('load', function () {
  document.body.style.background = '#111';
  document.body.style.filter = 'invert(1) hue-rotate(180deg)';
});