User script to restyle the OP's username in comments on Meta.SE so that it's circled by a red ellipse, as per http://meta.stackexchange.com/questions/229759/you-cant-see-the-question-owners-special-color/231282#231282.

metacircles.user.js

// ==UserScript==
// @name        Circle OP's username on Meta.SE
// @version     1.1
// @description Restyle the OP's username in comments on Meta.SE so that it's circled by a red ellipse.
// @namespace   https://github.com/vyznev/
// @author      Ilmari Karonen
// @license     ISC (http://opensource.org/licenses/ISC)
// @match       *://meta.stackexchange.com/*
// @grant       none
// @run-at      document-start
// ==/UserScript==

var css = 
    "a.comment-user.owner {\n" +
    "    border: 3px solid #faa;\n" +
    "    border-radius: 53% 47%;\n" +
    "    padding: 0.4em !important;  /* override existing padding style */\n" +
    "    margin: -0.4em;\n" +
    "    background: transparent;\n" +
    "}\n" +
    "span.comment-copy {\n" +
    "    position: relative;  /* keep username border from overlapping text */\n" +
    "}\n";

var style = document.createElement('style');
style.textContent = css;

var parent = (document.head || document.documentElement);
if (parent) parent.appendChild(style);
else {
  // work-around for https://github.com/greasemonkey/greasemonkey/issues/2996
  var obs = new MutationObserver(function () {
    var parent = (document.head || document.documentElement);
    if (parent) { obs.disconnect(); parent.appendChild(style); }
  });
  obs.observe(document, {childList: true});
}