Template for adding a style tag to the head of sites - e.g. for custom colour blind modes

styleAdder.js

// ==UserScript==
// @name         CSS adder
// @namespace    http://css.com/
// @version      0.1
// @description  Adds styles to a site
// @author       Marc A. Modrow
// @match        http*://*css.com*/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
    var colourblindCss = document.createElement("style");
    colourblindCss.innerHTML = '.greenStuff {\n  color: lime;\n}\n';
    document.querySelector("head").appendChild(colourblindCss);
})();