h5bp/html5-boilerplate — pull request #1144 by barneycarroll (2012-07-17 10:32:43+00:00)
Title: Image replacement transparency needs importance

Currently the premature optimisation technique fails whenever the element would have color inherited or directly specified via a selector with more precedence than the single class `.ir` (almost all the time, in my experience). Seeing as we can't second guess authors' methods for defining colours, important is necessary.

Explained in more detail here: https://github.com/h5bp/html5-boilerplate/commit/aa0396eae757c9e03dda4e463fb0d4db5a5f82d7#commitcomment-1591111