There is nothing like a 'breakpoint-specific class' in CSS
- http://benfrain.com/oocss-atomic-css-responsive-web-design-anti-pattern/
- http://philipwalton.com/articles/the-future-of-oocss-a-proposal/
- http://sass-guidelin.es/#extend
Generate suffix-classes - for one breakpoint each - on demand for a given class with the help of a preprocessor like Sass
http://thesassway.com/intermediate/using-object-oriented-css-with-sass- http://www.netorials.com/tutorials/object-oriented-css-responsive-web-design/