bootstrap variables not available in rails

Question

How do I get the @screen-sm @screen-md @screen-lg variables to work, and not give me errors? in rails using the bootstrap-sass gem?

When I remove the @screen-sm @screen-md @screen-lg variables and replace them with pixel values, the errors in my browser go away. But when I use these variables, the browser rails error says these arguments are invalid.

I am using bootstrap-sasts 3.0.3.

I also have //=require bootstrap in my application.js file. The github page https://github.com/twbs/bootstrap-sass says doing so will cause variables to not be available in other files, but even when i removed this line from my js file, I still could not use the variables in my application.css.scss file.

application.css.scss

*= require_self
*= require_tree .
*/
@import "bootstrap";

/* Small devices (tablets, 768px and up) */
@media only screen and (min-width: @screen-sm){ 

}

/* Medium devices (desktops, 992px and up) */
@media only screen and (min-width: @screen-md){ 

}

/* Large devices (large desktops, 1200px and up) */
@media only screen and (min-width: @screen-lg){ 

}

Gemfile

    source 'https://rubygems.org'
    ruby "2.0.0"

    gem 'rails', '4.0.0'
    gem 'uglifier', '>= 1.3.0'
    gem 'sass-rails', '~> 4.0.0'
    gem 'coffee-rails', '~> 4.0.0'
    gem 'jquery-rails'
    gem 'turbolinks'
    gem 'jquery-turbolinks'
    gem 'jbuilder', '~> 1.2'
    gem 'sprockets-rails', :require => 'sprockets/railtie'

    group :doc do
      # bundle exec rake doc:rails generates the API under doc/api.
      gem 'sdoc', require: false
    end

    gem 'html2haml', '~> 1.0.1'
    gem 'haml-rails', '0.5.1'
    gem 'bootstrap-sass', '~> 3.0.3.0'

    gem 'figaro', '~> 0.7.0'
    gem 'nokogiri', '~> 1.6.0'
    gem 'paperclip', '~> 3.0'
    gem 'paperclip-dropbox', '>= 1.1.7'
    gem 'devise'

    group :development do
        # erubis is already included in action pack
        gem 'ruby_parser', '~> 3.1.1'
    end

    group :development, :test do
      gem 'sqlite3'
    end

    group :production do
      gem 'pg'
      gem 'rails_12factor'

      #gem 'aws-sdk', "~> 1.0"
    end

    # Use ActiveModel has_secure_password
    # gem 'bcrypt-ruby', '~> 3.0.0'

    # Use unicorn as the app server
    # gem 'unicorn'

    # Use Capistrano for deployment
    # gem 'capistrano', group: :development

    # Use debugger
    # gem 'debugger', group: [:development, :test]

Answer 1

Today I've bumped into the same problem. I think the root of the problem is that you are mixing syntax (Less vs sass).

If your are writing a Less oriented stylesheet variables are referenced using @ operator. Whereas writing stylesheet using scass (I've inferred that because the name of the file application.css.scss) variables are referenced using $.

So, your stylesheet must be written as follow:

...

@import "bootstrap";

/* Small devices (tablets, 768px and up) */
@media only screen and (min-width: $screen-sm){ 

}

...