Random background color from specified color array, plus ability to coordinate site elements to match.
Based on code from the following:
http://www.thecodepress.info/2013/05/change-background-color-on-every.html#.UbHqwpwYh3B
http://lab.clearpixel.com.au/2008/06/darken-or-lighten-colours-dynamically-using-php/