Getting custom fonts to work for Rails 5 app deployed to Heroku.

rails 5 asset pipeline management: fonts

I deployed to Heroku and custom fonts didn't work. Details of my starting point below.
Fixed in 2 steps:
1. In application.rb file, in class Application < Rails::Application, added:
      config.assets.paths << Rails.root.join("app","assets","fonts")
2. In application.scss file, in @font-face, changed src: url('...') to font-url('...'); e.g.:
      src: font-url('Aileron/Aileron-Regular.otf') format('opentype');

Redeployed to Heroku and custom fonts worked.
---
Starting point details (this all worked for a local deploy, but not when deployed on Heroku):

1.
Custom font folders (one for each font family) added to the app/assets/fonts directory:
  daartly/app/assets/fonts/Aileron
  daartly/app/assets/fonts/Megrim
2.
Fonts added to the application.scss file:
 @font-face {
   font-family: 'Aileron';
   src: url('Aileron/Aileron-Regular.otf') format('opentype');
 }
 @font-face {
   font-family: 'AileronLight';
   src: url('Aileron/Aileron-Light.otf') format('opentype');
 }
 @font-face {
   font-family: 'AileronHeavy';
   src: url('Aileron/Aileron-Heavy.otf') format('opentype');
 }
 @font-face {
   font-family: 'AileronThin';
   src: url('Aileron/Aileron-Thin.otf') format('opentype');
 }
 @font-face {
   font-family: 'Megrim';
   src: url('Megrim/Megrim.ttf') format('truetype');
 }
 
3.
Fonts used in css classes using font-family; e.g.:
 header {
   font-family: "AileronLight";
   font-size: .8em;
   background-color: none;/* #f2bf2b;*/
 }
 
 4.
 Fonts used directly in html 'style' attributes with font-family (as in the css classes).

Thank you!