Fastmail monospace mail font

fastmail.user.js

// ==UserScript==
// @name         fastmail monospace
// @namespace    http://zirk.me/userscript
// @version      0.1
// @description  try to take over the world!
// @author       Arti
// @match        https://www.fastmail.com/mail/*
// @grant        none
// ==/UserScript==

(function() {
    var css = [
	"pre.u-article {",
	"    font-family: monospace;",
	"}",
	"",
	"textarea.v-Text-input {",
	"    font-family: monospace;",
	"}"
    ].join("\n");

    var node = document.createElement("style");
	node.type = "text/css";
	node.appendChild(document.createTextNode(css));
	var heads = document.getElementsByTagName("head");
	if (heads.length > 0) {
		heads[0].appendChild(node);
	} else {
		// no head yet, stick it whereever
		document.documentElement.appendChild(node);
	}
})();