Some small improvements for posteo.de webmailer (use calendar event color as background instead of border only, remove elements that waste screen space)

Posteo.user.js

// ==UserScript==
// @name         Posteo
// @author       jayme-github
// @copyright    2015+, jayme-github
// @namespace    https://github.com/jayme-github/
// @downloadURL  https://gist.github.com/jayme-github/65fa98d25f29062f5861/raw/Posteo.user.js
// @version      0.1
// @description  Some small improvements for posteo.de webmailer
// @match        https://posteo.de/webmail*
// @match        https://posteo.de/hilfe*
// @match        https://posteo.de/konto
// @match        https://posteo.de/notes
// @grant        none
// ==/UserScript==
/* jshint -W097 */
'use strict';

$(document).ready(function() {
    $("#topline").remove();
    $(".p_topline").remove();
    $("#messagetoolbar").css('height', '35px');

    if (document.URL.toLowerCase().indexOf("plugin.calendar") >= 0) {
        (function ($) {
            /**
            * @function
            * @property {object} jQuery plugin which runs handler function once specified element is inserted into the DOM
            * @param {function} handler A function to execute at the time when the element is inserted
            * @param {bool} shouldRunHandlerOnce Optional: if true, handler is unbound after its first invocation
            * @example $(selector).waitUntilExists(function);
            */
            $.fn.waitUntilExists	= function (handler, shouldRunHandlerOnce, isChild) {
                var found	= 'found';
                var $this	= $(this.selector);
                var $elements	= $this.not(function () { return $(this).data(found); }).each(handler).data(found, true);
                if (!isChild)
                {
                    (window.waitUntilExists_Intervals = window.waitUntilExists_Intervals || {})[this.selector] =
                        window.setInterval(function () { $this.waitUntilExists(handler, shouldRunHandlerOnce, true); }, 500)
                    ;
                }
                else if (shouldRunHandlerOnce && $elements.length)
                {
                    window.clearInterval(window.waitUntilExists_Intervals[this.selector]);
                }
                return $this;
            }
        }(jQuery));
        
        $("#messagetoolbar").css('top', '28px');
        $("#calquicksearchbar").css('top', '50px');
        $("#mainscreen").css('top', '90px');
        $("#calendar-header").css('top', '90px'); 
        $("a.fc-event").waitUntilExists(function(){
            $(this).css('background-color', $(this).css('border-color'));
        });
    } else {
        $("#mainscreen").css('top', '50px');
        $("#mailboxcontainer").css('top', '40px');
        $("#mailview-top").css('top', '40px');
    }
});