message: fix: add css property fallbacks in unstable
diff: @@ -11,7 +11,13 @@ const { defaultSchemeId } = require('./package.json');
  let plugins = [
  cssImport(),
  checkKeyframes(),
  - cssCustomProperties({ preserve: true }),
  + cssCustomProperties({
  + importFrom: [
  + path.join(__dirname, 'src/styles/bright_light.css'),
  + path.join(__dirname, 'src/styles/constants.css'),
  + ],
  + preserve: true
  + }),
  // postcss-custom-properties only works with :root
  scopeRoot({
  customPropRoot: '.vkui__root, .vkui__portal-root',
  