As you may already know, Firefox is one of the best web-browsers for Moodle users; Firefox properly loads the HTMLArea text editor, renders pages more consistently and is a safe and secure browser. Now you can theme your browser to match the open source software you use as a Learning Management System.
Firefox Personas are an add-on to the popular open source web-browser that let you add various themes to your browsing experience. Recently Lewis Carr created a Moodle Persona for Firefox which is attractive and functional: http://lewiscarr.co.uk/content/moodle-persona-firefox-36.
The Moodle Persona features the standard Moodle with mortar board and additional floating mortar boards over a dark grey background.