Using FontAwesome with Rails was really easy with font-awesome-rails gem. It also had really nice helpers. Thing is this gem depends on Sprokets. I wanted to try the shiny but very light Propshaft to be inline with modern Rails.
Developing email templates and sending a new mail every time to view a change is very inefficient and painful. Rails comes in rescue again. With mailer preview, you can view the changes in your browser just like any other page template.