Untitled

// ==UserScript==
// @name           Google+ after coming Calendar CSS fix
// @namespace      org.dronix.greasemonkey.calendar
// @include        https://www.google.com/calendar/*
// ==/UserScript==

var allDivs, thisDiv;
allDivs = document.evaluate(
    "//div[@class='tg-today']",
    document,
    null,
    XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE,
    null);

for (var i = 0; i < allDivs.snapshotLength; i++) {
    thisDiv = allDivs.snapshotItem(i);
    thisDiv.style.backgroundColor="yellow";
}