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  Be sure to have a copy of the AUI stylesheet available on your
  application, you can get it on https://docs.atlassian.com/aui/latest

  Inside your views, please add fieldset tag, and wrapper your submit or cancel 
  under a div that class is field_group
  as the following:

    = simple_form_for @user do |form|
     %fieldset
      = f.input :name
      = f.input :description, :as => :text_area

      .field_group
        = f.submit :class => "aui-button aui-button-primary"
        = link_to "Cancel", "", :class => "aui-button aui-button-link"

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