proxylist.user.js

// ==UserScript==
// @name         ProxyList
// @match        https://www.sslproxies.org/
// ==/UserScript==

(function() {
    'use strict';

    var list = document.getElementsByTagName("td");
    for (let item of list) {
        if (item.textContent == "anonymous") {
            item.parentElement.style.backgroundColor = "#fdd";
        }
    }
})();