How can I import external CSS files into my Ember app?

I am trying to import Font Awesome and Google Fonts into my Ember app but they aren't working. None of the styles are being applied.

I am using ember-cli-sass. Am I not able to import a stylesheet from a CDN? Does it not compile .css files? I tried looking for a .scss file for Font Awesome on a CDN but I couldn't find any, and I don't think Google offers .scss files at all.

app.js

import 'fonts.scss'

fonts.scss

@import '//maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css';
@import '//fonts.googleapis.com/css?family=Open+Sans:400,600,700,800,300';

When I add <i class="fa fa-user"></i> to my template, none of the Font Awesome styles are applied. Why aren't the stylesheets being imported?