postcss-logical

PostCSS Logical Properties and Values

npm install postcss-logical --save-dev

PostCSS Logical Properties and Values lets you use logical, rather than physical, direction and dimension mappings in CSS, following the CSS Logical Properties and Values specification.

.element {
	block-size: 100px;
	max-inline-size: 400px;
	inline-size: 200px;
	padding-block: 10px 20px;
	margin-inline: auto;
	border-block-width: 2px;
	border-block-style: solid;
}

/* becomes */

.element {
	height: 100px;
	max-width: 400px;
	width: 200px;
	padding-top: 10px;
	padding-bottom: 20px;
	margin-left: auto;
	margin-right: auto;
	border-top-width: 2px;
	border-bottom-width: 2px;
	border-top-style: solid;
	border-bottom-style: solid;
}

Usage

Add PostCSS Logical Properties and Values to your project:

npm install postcss postcss-logical --save-dev

Use it as a PostCSS plugin:

const postcss = require('postcss');
const postcssLogical = require('postcss-logical');

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

Options

blockDirection and inlineDirection

The blockDirection and inlineDirection options allow you to specify the direction of the block and inline axes. The default values are top-to-bottom and left-to-right respectively, which would match any latin language.

You should tweak these values so that they are specific to your language and writing mode.

postcssLogical({
	blockDirection: 'right-to-left',
	inlineDirection: 'top-to-bottom'
})

.element {
	block-size: 100px;
	max-inline-size: 400px;
	inline-size: 200px;
	padding-block: 10px 20px;
	margin-inline: auto;
	border-block-width: 2px;
	border-block-style: solid;
}

/* becomes */

.element {
	width: 100px;
	max-height: 400px;
	height: 200px;
	padding-right: 10px;
	padding-left: 20px;
	margin-top: auto;
	margin-bottom: auto;
	border-right-width: 2px;
	border-left-width: 2px;
	border-right-style: solid;
	border-left-style: solid;
}

Each direction must be one of the following:

• top-to-bottom
• bottom-to-top
• left-to-right
• right-to-left

You can't mix two vertical directions or two horizontal directions so for example top-to-bottom and right-to-left are valid, but top-to-bottom and bottom-to-top are not.

Please do note that text-align won't be transformed if inlineDirection becomes vertical.

ignoreCustomProperties

The ignoreCustomProperties option allows you to ignore any properties containing var().
postcss-logical assumes that all custom properties are single value (e.g. --foo: 10px;) and will assign these to physical properties as fallbacks for logical properties.

This will produce broken declarations when your custom properties contain multiple values instead (e.g. --foo: 1px 2px;).

:root {
	--inset-a: 10px;
}

.foo {
	inset: var(--inset-a);
}

:root {
	--inset-b: 1px 2px 3px 4px;
}

.bar {
	inset: var(--inset-b);
}

/* becomes */

:root {
	--inset-a: 10px;
}

.foo {
	top: var(--inset-a);
	right: var(--inset-a);
	bottom: var(--inset-a);
	left: var(--inset-a);
}

:root {
	--inset-b: 1px 2px 3px 4px;
}

.bar {
	top: var(--inset-b);
	right: var(--inset-b);
	bottom: var(--inset-b);
	left: var(--inset-b);
}

With ignoreCustomProperties set to true:

:root {
	--inset-a: 10px;
}

.foo {
	inset: var(--inset-a);
}

:root {
	--inset-b: 1px 2px 3px 4px;
}

.bar {
	inset: var(--inset-b);
}

/* becomes */

:root {
	--inset-a: 10px;
}

.foo {
	inset: var(--inset-a);
}

:root {
	--inset-b: 1px 2px 3px 4px;
}

.bar {
	inset: var(--inset-b);
}

Similar packages

Other packages similar to postcss-logical

postcss-dir-pseudo-class

This package also facilitates writing directional CSS by providing a way to define styles for different directions using :dir() pseudo-class. It is similar to postcss-logical but focuses more on pseudo-classes rather than property conversions.

rtlcss

RTL CSS is a framework for transforming LTR CSS to RTL. It's more comprehensive than postcss-logical as it includes a wider range of transformations and configurations, making it suitable for complex RTL adaptations.