Violentmonkey script for slightly bumping up the font size when editing code on GitHub on my M1 MacBook Pro.

GitHub-code-font-size.js

// ==UserScript==
// @name GitHub source editing font size on my M1 MacBook Pro.
// @description For some reason the font size is a little too small _only_ when editing in the source view.
// @author Lucas Costi
// @namespace https://lucascosti.com
// @match https://github.com/*/*/edit/*
// @match https://github.com/*/*/new/*
// @match https://gist.github.com/*/*/edit
// @match https://gist.github.com/
// @grant none
// ==/UserScript==
//
//

// The div for lines of code has the class CodeMirror-lines
const divs = document.querySelectorAll(".CodeMirror-lines");

divs.forEach((element) => {
  element.style.fontSize = "13px";
});