Issue reproduction for postcss hmr

Reproduction for farm-fe/farm#2024.

Way to reproduce

1. Install dependencies

   pnpm install

2. Start farm dev server

   pnpm dev

3. Open test link in browser

   Click and open http://localhost:9000/#/page. As we can see, the background is filled with gray.

4. Change class name in src/views/page.vue

   The original class is bg-gray-800, change it to bg-gray-900 or other background classes.

   You can see the background is white after change the class.

Platform

Arch Linux