When it comes to css frameworks you're not supposed to override the styles. Most of them give you an option to customize the setup or can be modified easily by changing a few SASS variables.
While that might be true, I do take it as a dis-advantage that the frameworks can't be easily overridden. I can just imagine the wasted minutes now, setting a font on the page only to watch it not change and wondering why pure would pick such specificity only to set the font to sans-serif. Imagine if they'd done that with the other bits? Made the styling so specific that you couldn't easily style on top of it.
Also I believe that Pure doesn't do the whole configure-with-sass thing -- though it can be customized, it's CSS only (https://github.com/yahoo/pure).
I wasn't aware of this shortcoming of Pure (maybe because I haven't used so many custom fonts), but I'm going to be keeping it in mind for the future.
