There are very few excuses to forgive anyone not using a preprocessor these days. Not only do preprocessors speed up the development process, but also, as Chris Coyier from css-tricks.com recently stated, “They make CSS fun again.”
At Rocket55 our developers use Compass, which is an open-source CSS authoring framework that uses SASS (a prepropressor), an extension of CSS3, which adds nested rules, variables, mixins, selector inheritance, and more. Sass generates well-formatted CSS and makes your stylesheets easier to organize and maintain.
Compass also has useful ways to create mixins for your breakpoints when creating responsive websites. This greatly reduces the amount of time you spend when developing your responsive designs and the generated css keeps all your styles and media queries together, which makes for easy editing in the future.
For more information about using compass and SASS, visit http://compass-style.org/