https://github.com/UseAllFive/true-visibility
Testing offset calcs
Initially based on code from https://github.com/UseAllFive/true-visibility Trying to debug and understand logic
Removing font top/bottom whitespace Based on... http://jsfiddle.net/7vNpJ/21/ http://stackoverflow.com/a/14061404
No-Library (pure JS), HTML, CSS, JavaScript