Add Font Spacing Requirements to the visual guidelines

[emanlove]

It would be good to add specific guidelines on the spacing in terms of numbers and percentages both in terms of css units but also various print and tools.

It should be noted that as software project, many us are either not graphics designers or are amateur "attempters" (thinking of myself here :) ). So really having exact details, at least a brief explanation with reference to articles elsewhere for a deeper understanding, and instructions for a variety of mediums (internet, print, etc) and tools (Gimp, Adobe Photoshop/Illustrator, Inkscape, others??) would really be helpful for our guidelines.