Synology chat dark mode script

.css

/* Remove this comment
*  Change "->CHAT_ADDRESS_HERE<-" to your synology chat address and install script below for that website.
*  If you're running desktop version, this will probably not work for you. I am running web version installed as an app in the browser
*/

// ==UserScript==
// @name         New Userscript
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        ->CHAT_ADDRESS_HERE<-
// @grant        none
// ==/UserScript==

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);
}

(function()
{
    'use strict';

    addGlobalStyle('.syno-chat .chat-content-panel .chat-center-content-panel {background: #222222; color: #DDDDDD; }');
    addGlobalStyle('.syno-chat .chat-msgview .msg-wrap .msg-text,' +
                   '.syno-chat .chat-msgview .msg-wrap .msg-user-name,' +
                   '.syno-chat .chat-content-panel .chat-msg-top-toolbar .msg-title,'+
                   '.syno-chat .chat-msgview .msg-wrap .file-wrapper .file-desc,'+
                   '.syno-chat .chat-msgview .msg-wrap .file-wrapper .msg-file-name {color: #DDDDDD; }');
    addGlobalStyle('.syno-chat .chat-msgview .msg-wrap:hover, .syno-chat .chat-modal-window {background: #888888; }');
    addGlobalStyle('.syno-chat .chat-input-aria-main, .syno-chat .syno-ux-contenteditable {background: #444444; color: #DDDDDD }');
    addGlobalStyle('.syno-chat .chat-msgview .extra-date-splitter-wrapper {background-color: #444444; }');
})();