Bootstrap

Ember

$ ember install ember-cli-sass
$ yarn add --dev bootstrap
$ mv app/styles/app.{,s}css

ember-cli-build.js

 module.exports = function (defaults) {
   let app = new EmberApp(defaults, {
+    sassOptions: {
+      includePaths: ['node_modules/bootstrap/scss'],
+    },
   });

app.scss

$primary: rgb(255, 235, 59);

@import 'bootstrap';