You can disable CSS animations and transitions globally by setting the Capybara.disable_animation option.

Stick this in your rails_helper.rb:

Capybara.disable_animation = true

Instead of a boolean, you can set this option to a CSS selector and it will only disable animations that match that selector:

Capybara.disable_animation = '#with_animation a'

For a better understanding of how this works take a look at the tests for Capybara.disable_animation in the Capybara source code.