PostCSS Stepped Value Functions

npm install @csstools/postcss-stepped-value-functions --save-dev

PostCSS Stepped Value Functions lets you use round, rem and mod stepped value functions, following the CSS Values 4 specification.

.test-functions {
	padding: 8px mod(18px, 5px) 1px calc(rem(15px, 6px) + 50%);
	transform: rotate(mod(-140deg, -90deg));
	top: round(15px, 4px);
	right: round(nearest, 15px, 4px);
	bottom: round(up, 15px, 7px);
	left: round(down, 15px, 4px);
	width: round(to-zero, 15px, 4px);
}

/* becomes */

.test-functions {
	padding: 8px 3px 1px calc(3px + 50%);
	transform: rotate(-50deg);
	top: 16px;
	right: 16px;
	bottom: 21px;
	left: 12px;
	width: 12px;
}

Usage

Add PostCSS Stepped Value Functions to your project:

npm install postcss @csstools/postcss-stepped-value-functions --save-dev

Use it as a PostCSS plugin:

const postcss = require('postcss');
const postcssSteppedValueFunctions = require('@csstools/postcss-stepped-value-functions');

postcss([
	postcssSteppedValueFunctions(/* pluginOptions */)
]).process(YOUR_CSS /*, processOptions */);

⚠️ About custom properties

Given the dynamic nature of custom properties it's impossible to know what the variable value is, which means the plugin can't compute a final value for the stylesheet.

Because of that, any usage that contains a var is skipped.

Options

preserve

The preserve option determines whether the original notation is preserved. By default, it is not preserved.

postcssSteppedValueFunctions({ preserve: true })

.test-functions {
	padding: 8px mod(18px, 5px) 1px calc(rem(15px, 6px) + 50%);
	transform: rotate(mod(-140deg, -90deg));
	top: round(15px, 4px);
	right: round(nearest, 15px, 4px);
	bottom: round(up, 15px, 7px);
	left: round(down, 15px, 4px);
	width: round(to-zero, 15px, 4px);
}

/* becomes */

.test-functions {
	padding: 8px 3px 1px calc(3px + 50%);
	padding: 8px mod(18px, 5px) 1px calc(rem(15px, 6px) + 50%);
	transform: rotate(-50deg);
	transform: rotate(mod(-140deg, -90deg));
	top: 16px;
	top: round(15px, 4px);
	right: 16px;
	right: round(nearest, 15px, 4px);
	bottom: 21px;
	bottom: round(up, 15px, 7px);
	left: 12px;
	left: round(down, 15px, 4px);
	width: 12px;
	width: round(to-zero, 15px, 4px);
}