csstoolsPostCSS Position Area Property 
npm install @csstools/postcss-position-area-property --save-dev
PostCSS Position Area Property lets you fallback position-area to the alternate name inset-area following the CSS Specification.
.foo {
position-area: start;
}
/* becomes */
.foo {
inset-area: start;
position-area: start;
}
Usage
Add PostCSS Position Area Property to your project:
npm install postcss @csstools/postcss-position-area-property --save-dev
Use it as a PostCSS plugin:
const postcss = require('postcss');
const postcssPositionAreaProperty = require('@csstools/postcss-position-area-property');
postcss([
postcssPositionAreaProperty(/* pluginOptions */)
]).process(YOUR_CSS /*, processOptions */);