Merge branch 'admin-improvements-and-styling-fixes' into 'main'

app/assets/stylesheets/application.tailwind.css

app/controllers/admin/base_controller.rb

app/controllers/admin/conferences_controller.rb

app/controllers/admin/dashboard_controller.rb

app/controllers/admin/roles_controller.rb

app/controllers/admin/users_controller.rb

app/helpers/button_helper.rb

app/models/import_history.rb

app/views/admin/conferences/_form.html.erb

app/views/admin/conferences/edit.html.erb

app/views/admin/conferences/import_history.html.erb

app/views/admin/conferences/index.html.erb

app/views/admin/conferences/new.html.erb

app/views/admin/conferences/select_relevant_stages.html.erb

app/views/admin/conferences/show.html.erb

app/views/admin/dashboard/index.html.erb

app/views/admin/roles/_form.html.erb

app/views/admin/roles/edit.html.erb

app/views/admin/users/_form.html.erb

app/views/admin/users/edit.html.erb