see: http://stackoverflow.com/questions/22047466/how-to-add-css-class-to-a-googlemaps-marker
author(s): Torstein Hønsi
jQuery 1.6.2, HTML, CSS, JavaScript
http://stackoverflow.com/q/8024784/918414
No-Library (pure JS), HTML, CSS, JavaScript
jQuery 1.9.1, HTML, CSS, JavaScript