Parsing error with complex custom properties

Start by reproducing the reported CSS custom-property example and tracing the parser error through the mentioned Parser.parse and Parser.pseudo entry points. Confirm that the complex custom property no longer triggers the selector-parser error, then verify the existing parsing behavior remains intact.

I am using postcss-preset-env which use this plugin and I am getting a parsing error when I have a "complex" custom property.

When a css file hat the following code:

:root{
  --myColor: green,
  --myInnerStyle: {
    font-family: "Open Sans", 'Helvetica Neue', Helvetica, Arial, sans-serif;
  }
}

I am getting this error:

ERROR in ./src/components/MyThemeOverride.css (./node_modules/css-loader??ref--10-1!./node_modules/postcss-loader/lib??postcss!./node_modules/sass-loader/lib/loader.js??ref--10-3!./src/components/MyThemeOverride.css)
Module build failed: Error: Expected a pseudo-class or pseudo-element.
at Root._error (C:\Git\client-react\node_modules\postcss-attribute-case-insensitive\node_modules\postcss-selector-parser\dist\parser.js:173:24)
at Root.error (C:\Git\client-react\node_modules\postcss-attribute-case-insensitive\node_modules\postcss-selector-parser\dist\selectors\root.js:43:25)
at Parser.error (C:\Git\client-react\node_modules\postcss-attribute-case-insensitive\node_modules\postcss-selector-parser\dist\parser.js:561:25)
at Parser.expected (C:\Git\client-react\node_modules\postcss-attribute-case-insensitive\node_modules\postcss-selector-parser\dist\parser.js:879:25)
at Parser.pseudo (C:\Git\client-react\node_modules\postcss-attribute-case-insensitive\node_modules\postcss-selector-parser\dist\parser.js:673:25)
at Parser.parse (C:\Git\client-react\node_modules\postcss-attribute-case-insensitive\node_modules\postcss-selector-parser\dist\parser.js:843:22)
at Parser.loop (C:\Git\client-react\node_modules\postcss-attribute-case-insensitive\node_modules\postcss-selector-parser\dist\parser.js:812:18)
at new Parser (C:\Git\client-react\node_modules\postcss-attribute-case-insensitive\node_modules\postcss-selector-parser\dist\parser.js:165:14)
at Processor._root (C:\Git\client-react\node_modules\postcss-attribute-case-insensitive\node_modules\postcss-selector-parser\dist\processor.js:47:22)
at Processor._runSync (C:\Git\client-react\node_modules\postcss-attribute-case-insensitive\node_modules\postcss-selector-parser\dist\processor.js:83:25)
@ ./src/components/MyThemeOverride.css 2:14-220 21:1-42:3 21:218-42:2 22:19-225
@ ./src/components/Root.js
@ ./src/index.js
@ multi ./src/webpack-public-path react-hot-loader/patch webpack-hot-middleware/client?reload=true ./src/index.js