Tep3

% ruby -v
% rbenv versions
% rbenv local 2.7.5
% rails -v

% rails new tep3 -d postgresql
database.yml username
rails db:create

$ yarn add bootstrap@next
$ yarn add @popperjs/core

app/javascript/packs/application.js
import "bootstrap";
import "../stylesheets/application";

% mkdir app/javascript/stylesheets/
% touch app/javascript/stylesheets/application.scss
@import "bootstrap";

app/views/layouts/application.html.erb
<%= stylesheet_pack_tag 'application', media: 'all', 'data-turbolinks-track': 'reload' %>