They are CJS modules or (ideally) Typescript. CSS custom properties (variables) are slightly different.

    import type { Config } from 'tailwindcss'
    
    export default {
      content: [],
      theme: {
        extend: {},
      },
      plugins: [],
    } satisfies Config

(not arguing for or against TW here)

Never said you did. I was just explaining that you aren't "using someone else's padding and margin classes".