[jammi]

Thanks, I converted it into a Tampermonkey userscript to use on all the sites.

  // ==UserScript==
  // @name         Underline links
  // @namespace    http://tampermonkey.net/
  // @version      0.1
  // @description  Underline all the links!
  // @author       mdaniel
  // @match        https://*/*
  // @match        http://*/*
  // @grant        none
  // ==/UserScript==

  (() => {
      document.querySelectorAll('a[href]').forEach(it => it.style.textDecoration='underline');
  })();