Clear and concise description of the problem

I have multiple CSS files that I process and add them to UnoCSS via rules or preflights.

I am finalizing migrating the content to the new colors structure. Some of the colors are defined in the CSS files only and added via preflights so the theme is not aware of those keys and does not generate the CSS variables.

Suggested solution

import { createRemToPxProcessor } from '@unocss/preset-wind4/utils'
import { defineConfig, presetWind4 } from 'unocss'

export default defineConfig({
  presets: [
    presetWind4({
      preflights: { 
        theme: { 
          safelist: ['colors:blue-500'], // will add --colors-blue-500 to :root
        } 
      }, 
    }),
  ],
})

Alternative

I am not really sure how to solve this in a clean way... I am trying something, but it is not working. See playground

• Setting mode:true

Additional context

No response

Validations

• Read the Contributing Guidelines.
• Read the README.md of using the package.
• Already used the Interactive Docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.