h5bp/html5-boilerplate — comment on commit aa0396eae757c9e03dda4e463fb0d4db5a5f82d7
File:  line 0
By jonathantneal:

@sjefull would you tell me how you are using ems? I am interested in knowing more about your use case.

In my projects, I use ems only when I am also using background-size. I have found that because the image is sized in pixels it is better to css size it in pixels too.