In article this article I’ll show you how to use Bootstrap 5 in Rails 7

JavaScript:

$ bin/importmap pin bootstrap

// app/javascript/application.js
// ...
import 'bootstrap'

CSS:

# Gemfile
# ...
gem 'bootstrap', '~> 5.1.3'
# ...

// app/assets/stylesheets/application.scss
// ...
@import "bootstrap";
// ...

https://blog.eq8.eu/til/how-to-use-bootstrap-5-in-rails-7.html