SASS / SCSS (Syntactically Awesome StyleSheets)

SASS (SCSS) is a CSS extension language 

SCSS SYNTAX

$font-stack:    Helvetica, sans-serif;
$primary-color: #333;

body {
  font: 100% $font-stack;
  color: $primary-color;
}

"Sass is an extension of CSS that adds power and elegance to the basic language. It allows you to use variables, nested rules, mixins, inline imports, and more, all with a fully CSS-compatible syntax. Sass helps keep large stylesheets well-organized, and get small stylesheets up and running quickly, particularly with the help of the Compass style library." - I agree :)

Sass / Scss documentation here

Important notes

 - by Scss possible to break css to blocks, and ,after build, will created single file, Possble to split work between team, components. And, thus, can be used in Style Guides Generators like  Patters lab

Possible integrated to WebStorm - on scss save, on build event, to VS with several extension