Analytical Engine

typ.io is a cool gallery of typeface pairs

to avoid getting the "stack level too deep" error with factory girl, you must avoid circular relationships between your factories. You can use factory girl callbacks to lazily fill in these relationships only if they don't already exist:

FactoryGirl.define do
    factory :author do
      posts { [FactoryGirl.build(:post)] }
    end

    factory :post do
      before(:create) do |post|
        post.author = FactoryGirl.build(:author) if post.author.nil?
      end
    end
  end

i wrote a post about what is new with Rails 4.2 for the Revelry blog

if you need help picking a body font, this article is a great summary of what to look for

don't know about offline first web apps?

this reading list is a great place to start

this is a nice bite-sized introduction to CSS variables

the title is silly though, because his examples can definitely be done efficiently in SASS