Ever make a tiny css change, push it to production, and then discover that it completely wrecks another page's style? Good CSS discipline can reduce that problem, but things still slip through... and it's expensive to hire someone to check every page for visual errors.
Percy lets you put that visual check into your test suite. Discover how.
Also, this is an experiment- co-hosting a screencast with the author on an addon. Let me know what you think. And if you want your addon featured on EmberScreencasts- and you have 2-4 hours to spare- email me at firstname.lastname@example.org.