citrusbyte/css-styleguide — pull request #1 by dkullmann (2014-11-08 18:30:28+00:00)
Title: Unitless line-heights

Throughout this doc you mention using `em` instead of `px` for line-height, but there's actually drawbacks to using a unit with line-height. Figured I'd pass this on: http://meyerweb.com/eric/thoughts/2006/02/08/unitless-line-heights/

(fairly old article but i've still heard people say the same thing recently)