Internal server error: [postcss] postcss-import: Unknown word

[zAlweNy26]

Environment

• Operating System: Linux
• Bun Version: v1.1.29
• Vue Version: v3.5.13
• Vite Version: v5.4.11
• Package Manager: bun@1.1.29

Is this bug related to Nuxt or Vue?

Vue

Version

v3.0.0-alpha.9

Reproduction

Unable to run on https://stackblitz.com/edit/vitejs-vite-2s99rp because of stackblitz/core#1855 (I think) but I'll create a repo as soon as I can.

Description

After following the setup tutorial for the installation of Nuxt UI in a Vue-only environment and running the project, I get an error (see logs).
The only different thing in the setup I had to do is that, as I am building a custom element, I did:

const Widget = defineCustomElement(App, {
	configureApp(app) {
		app.use(ui)
		app.use(i18n)
		app.provide(I18nInjectionKey, i18n)
	},
})

Instead of the usual createApp method. Did I miss something?

Additional context

No response

Logs

15:53:45 [vite] Internal server error: [postcss] postcss-import: /home/dany/Documenti/GitHub/chat-widget/node_modules/@nuxt/ui/dist/module.mjs:1:16: Unknown word
  Plugin: vite:css
  File: /home/dany/Documenti/GitHub/chat-widget/node_modules/@nuxt/ui/dist/module.mjs:1:15
  1  |  import defu, { defu as defu$1 } from 'defu';
     |                 ^
  2  |  import { defineNuxtModule, createResolver, addVitePlugin, addPlugin, addComponentsDir, addImportsDir, extendPages, hasNuxtModule, installModule } from '@nuxt/kit';
  3  |  import { d as defaultOptions, r as resolveColors, a as getDefaultUiConfig, b as addTemplates, c as buildTemplates } from './shared/ui.d52SSCwA.mjs';
      at Input.error (/home/dany/Documenti/GitHub/chat-widget/node_modules/postcss/lib/input.js:106:16)
      at Parser.unknownWord (/home/dany/Documenti/GitHub/chat-widget/node_modules/postcss/lib/parser.js:593:22)
      at Parser.other (/home/dany/Documenti/GitHub/chat-widget/node_modules/postcss/lib/parser.js:435:12)
      at Parser.parse (/home/dany/Documenti/GitHub/chat-widget/node_modules/postcss/lib/parser.js:470:16)
      at parse (/home/dany/Documenti/GitHub/chat-widget/node_modules/postcss/lib/parse.js:11:12)
      at get root [as root] (/home/dany/Documenti/GitHub/chat-widget/node_modules/postcss/lib/no-work-result.js:119:14)
      at Result.get [as root] (/home/dany/Documenti/GitHub/chat-widget/node_modules/postcss/lib/no-work-result.js:27:21)
      at loadImportContent (file:///home/dany/Documenti/GitHub/chat-widget/node_modules/vite/dist/node/chunks/dep-C6EFp3uH.js:867:33)
      at async Promise.all (index 0)
      at async resolveImportId (file:///home/dany/Documenti/GitHub/chat-widget/node_modules/vite/dist/node/chunks/dep-C6EFp3uH.js:800:27)
15:53:45 [vite] Pre-transform error: [postcss] postcss-import: /home/dany/Documenti/GitHub/chat-widget/node_modules/@nuxt/ui/dist/module.mjs:1:16: Unknown word

[izoukhai]

I have the exact same issue when trying to use Tailwinds's @source "PATH"