PreCSS

PreCSS is a tool that allows you to use Sass-like markup in your CSS files.

Enjoy a familiar syntax with variables, mixins, conditionals, and other goodies.

Variables

/* before */

$blue: #056ef0;
$column: 200px;

.menu {
	width: calc(4 * $column);
}

.menu_link {
	background: $blue;
	width: $column;
}

/* after */

.menu {
	width: calc(4 * 200px);
}

.menu_link {
	background: #056ef0;
	width: 200px;
}

Conditionals

/* before */

.notice--clear {
	@if 3 < 5 {
		background: green;
	}
	@else {
		background: blue;
	}
}

/* after */

.notice--clear {
	background: green;
}

Loops

/* before */

@for $i from 1 to 3 {
	.b-$i { width: $(i)px; }
}

/* after */

.b-1 {
	width: 1px
}
.b-2 {
	width: 2px
}
.b-3 {
	width: 3px
}

/* before */

@each $icon in (foo, bar, baz) {
	.icon-$(icon) {
		background: url('icons/$(icon).png');
	}
}

/* after */

.icon-foo {
	background: url('icons/foo.png');
}

.icon-bar {
	background: url('icons/bar.png');
}

.icon-baz {
	background: url('icons/baz.png');
}

Mixins

/* before */

@define-mixin icon $name {
	padding-left: 16px;

	&::after {
		content: "";
		background-url: url(/icons/$(name).png);
	}
}

.search {
	@mixin icon search;
}

/* after */

.search {
	padding-left: 16px;
}

.search::after {
	content: "";
	background-url: url(/icons/$(name).png);
}

Extends

/* before */

@define-extend bg-green {
	background: green;
}

.notice--clear {
	@extend bg-green;
}

/* after */

.notice--clear {
	background: green;
}

Imports

/* Before */

@import "partials/_base.css"; /* Contents of _base: `body { background: black; }` */


/* After */

body { background: black; }

Usage

You just need to follow these two steps to use PreCSS:

Add PostCSS to your build tool.
Add PreCSS as a PostCSS process.

npm install precss --save-dev

Node

postcss([ require('precss')({ /* options */ }) ])

Grunt

Add Grunt PostCSS to your build tool:

npm install precss --save-dev

Enable PreCSS within your Gruntfile:

grunt.loadNpmTasks('grunt-postcss');

grunt.initConfig({
	postcss: {
		options: {
			processors: [
				require('precss')({ /* options */ })
			]
		},
		dist: {
			src: 'css/*.css'
		}
	}
});

Options

...

travco/precss