Ruby project - Sass::SyntaxError - Undefined mixin 'box-shadow'

I am making ruby on rails project, and after I added some gems:

gem 'activeadmin', github: 'gregbell/active_admin'
gem 'devise'
gem 'active_admin_editor' 
gem 'font-awesome-rails'
gem 'bootstrap-sass', '~>3.2.0'
gem 'autoprefixer-rails'

and run bundle install and rails g active_admin:install, and also installed node.js, and restarted application, I got error:

Sass::SyntaxError in Home#show

Showing /home/user/railscmsproject/app/views/layouts/application.html.erb where line #8 raised:

Undefined mixin 'box-shadow'.

Extracted source (around line #8):
    <%= csp_meta_tag %>

8    <%= stylesheet_link_tag    'application', media: 'all', 'data-turbolinks-track': 'reload' %>
    <%= javascript_include_tag 'application', 'data-turbolinks-track': 'reload' %>

I tried to change 'application' in row 8 in application.html.erb to 'default' it did not solve the problem.

Also I tried in file active_admin.css to change

@import "active_admin/mixins";
@import "active_admin/base";


@import "active_admin/mixins.css";
@import "active_admin/base.css";

it did not solve the problem.

Should I add in some css file this code?

@mixin box-shadow($value) {
        -webkit-box-shadow: $value;
        -moz-box-shadow: $value;
        box-shadow: $value;