PostCSS Logical Viewport Units

npm install @csstools/postcss-logical-viewport-units --save-dev

PostCSS Logical Viewport Units lets you easily use vb and vi length units following the CSS-Values-4 Specification.

.foo {
    margin: 10vi 20vb;
}

/* becomes */

.foo {
    margin: 10vw 20vh;
    margin: 10vi 20vb;
}

Usage

Add PostCSS Logical Viewport Units to your project:

npm install postcss @csstools/postcss-logical-viewport-units --save-dev

Use it as a PostCSS plugin:

const postcss = require('postcss');
const postcssLogicalViewportUnits = require('@csstools/postcss-logical-viewport-units');

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

Options

inlineDirection

The inlineDirection option allows you to specify the direction of the inline axe. The default value is left-to-right, which would match any latin language.

You should tweak this value so that it is specific to your language and writing mode.

postcssLogicalViewportUnits({
    inlineDirection: 'top-to-bottom'
})

.foo {
    margin: 10vi 20vb;
}

/* becomes */

.foo {
    margin: 10vh 20vw;
    margin: 10vi 20vb;
}

Each direction must be one of the following:

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

Please do note that transformations won't do anything particular for right-to-left or bottom-to-top.

preserve

The preserve option determines whether the original notation is preserved. By default, it is preserved.

postcssLogicalViewportUnits({ preserve: false })

.foo {
    margin: 10vi 20vb;
}

/* becomes */

.foo {
    margin: 10vw 20vh;
}