Edit file File name : postcss.config.js Content :module.exports = () => ( { plugins: [ require( '@csstools/postcss-global-data' )( { // Provide the properties that postcss-custom-properties is going to work with. files: [ require.resolve( '@automattic/calypso-color-schemes/root-only/index.css' ) ], } ), require( 'postcss-custom-properties' )( { // Use of `preserve: false` dates back to when we still used @automattic/calypso-build. // Ideally we'd get rid of it to properly make use of CSS vars, but first we have to // figure out how to ensure the vars actually get defined in the browser without // including them in every bundle. Some base stylesheet (wp_register_style) the other // stylesheets depend on maybe? And also deal with extremely generic vars like "--color-text". // // See also https://github.com/Automattic/jetpack/pull/13854#issuecomment-550898168, // where people were confused about what was going on when calypso-build stopped // including a postcss.config.js like this by default. preserve: false, } ), require( 'autoprefixer' ), ], } ); Save