Here are some of the highlights:
Make sure Bootstrap 4 is installed, either as a Ruby gem or using CDN:
Add this line to your application's Gemfile:
gem 'devise-bootstrap-views', '~> 1.0'
And then execute:
$ bundle install
Install devise-i18n for other locales. Make sure to insert
gem 'devise-bootstrap-views', see #55.
devise:views:bootstrap_templatesgenerator will copy all views to your application, so you can modify the files as you wish:
$ rails generate devise:views:bootstrap_templates
git checkout -b my-new-feature)
git commit -am 'Add some feature')
git push origin my-new-feature)