April fools knight for Lichess

lichess_knight.js

// ==UserScript==
// @name         Use the april fools knight, as knight on the board.
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  improves rating by 1000
// @author       Shibe
// @match        https://lichess.org/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    function addGlobalStyle(css) {
        var head, style;
        head = document.getElementsByTagName('head')[0];
        if (!head) { return; }
        style = document.createElement('style');
        style.type = 'text/css';
        style.innerHTML = css;
        head.appendChild(style);
    };

    addGlobalStyle(
        '.is2d .knight.white { background-image: url(https://i.imgur.com/gCXGXXi.png); }' +
        '.is2d .knight.black { background-image: url(https://i.imgur.com/AL2qSlJ.png); }'
    );
})();