grease

// ==UserScript==
// @name        stacktest
// @namespace   stacktest
// @description stacktest
// @include https://fiddle.jshell.net/wsqq7wfz/3/show/light/
// @version     1
// @grant       none
// ==/UserScript==


var thetds = document.getElementsByTagName('td');
for (var j = 0; j < thetds.length; j++) {
if (thetds[j].innerHTML == "May")
    thetds[j].style.backgroundColor = "rgb(250, 0, 0)";
}