Before you start writing any code, you’ve got design issues that matter not just to aesthetics, but to the reader’s comprehension of the presentation. So how do you choose color? What colors are the “right ones”? The key is that color is relational. In any composition or layout, a single color does not exist in a vacuum, but is always comprehended in relation to the other colors present. - See more at: http://datadrivenjournalism.net/resources/colour_theory_and_mapping#sthash.7ACnqZdQ.dpuf