This plugin requires vite of v3 or greater. It only makes sense to use if you're using css modules.

$ npm install --save-dev vite-plugin-optimize-css-modules

In your vite.config.ts simply add the plugin:

import { optimizeCssModules } from 'vite-plugin-optimize-css-modules';
import { defineConfig } from 'vite';

export default defineConfig({
    plugins: [
        optimizeCssModules()
    ]
})

And that's it. When running vite build your generated CSS should be significantly smaller.

By default, when using css modules, you end up with hashes or other long class-names in your bundled css files:

@keyframes _close-card_pzatx_1 {
    /* ...css */
}

._card_pzatx_32 {
    /* ...css */
}

._back_pzatx_49 ._content_pzatx_70 ._close_pzatx_74 {
    /* ...css */
}

By using this module, the smalles possible classname will be used for each "id":

@keyframes a {
    /* ...css */
}

.v {
    /* ...css */
}

.c .s .w {
    /* ...css */
}