h5bp/html5-boilerplate — Issue #958: Consider changing print color to #333333
Author: Umber
Created: 2012-02-02 18:17:54+00:00
State: open

According to h5bp.com/s all browsers can handle greyscales upto #6B6B6B as the minimum.
So #333333 is well within that range. The reason for changing it is that while #333333 is still dark enough it also saves a little ink with each print job. Worldwide this can save a lot of ink = a lot of energy. Basically; it's greener.
However, I did not test this value in all browsers, so there may be a snag.