http://compass-style.org/reference/compass/css3/font_face/#mixin-font-face
Setting weights and styles http://coding.smashingmagazine.com/2013/02/14/setting-weights-and-styles-at-font-face-declaration
Source Sans Pro Regular
http://compass-style.org/reference/compass/css3/font_face/#mixin-font-face
Setting weights and styles http://coding.smashingmagazine.com/2013/02/14/setting-weights-and-styles-at-font-face-declaration
Source Sans Pro Regular