SASS

SASS or SCSS is a CSS preprocessor. It allows you to use variables, functions, and other features that don’t exist in plain CSS.

To install SASS, run:

npm install -g sass

To compile a .scss file to .css, run:

sass file.scss file.css

If you want to compile a .scss file to .css and watch for changes, run:

sass --watch file.scss file.css

Essentialy valid CSS is valid SCSS

Variables

$color: #000;

body {
  background-color: $color;
}