Supposedly Google is going to lower the rank of sites that aren’t mobile friendly:
http://www.theguardian.com/technology/2015/apr/20/google-mobilegeddon-will-shake-up-mobile-search-results
I noticed a bunch of atom.io pages do not pass their tester/checker.
packages:
https://www.google.com/webmasters/tools/mobile-friendly/?url=https%3A%2F%2Fatom.io%2Fpackages
docs:
https://www.google.com/webmasters/tools/mobile-friendly/?url=https%3A%2F%2Fatom.io%2Fdocs
A few of the individual packages I checked fail as well.
(homepage and discuss.atom.io do pass)
Just giving a heads up!