If you've set up the application with the `vendor/assests/stylesheets/pdf.css` and have this set to complile separately, you can download the CSS from https://getbootstrap.com/docs/3.3/customize/?id=08c164bd0450fe50e9bf and paste it into the `pdf.css`. This is what I'm using. You can probably also do the same for bootstrap 4.1, but the important bits would be the things selected where it is mainly the media styles, grid, typography, etc.

Personally, I would try to keep the styling in the email simple. Supporting rendering on different email clients is very difficult since there are definitely more email clients than browsers. Check out https://www.campaignmonitor.com/css for individual styling compatibility for mail clients.

The services class was done in https://www.driftingruby.com/episodes/rails-api-app-authentication-with-json-web-tokens

I have three more planned for the moment. 1. Adding nested comments 2. Activity Feed 3. ActionCable tie-ins The activity feeds and ActionCable ones will probably come out in December. If there is interest, I've been thinking about also doing an episode of taking a Bootstrap "Theme" and showing how to incorporate it within the application.

Any themes in mind? One of my thoughts were https://coreui.io/