Esbuild not flattening nested CSS

I’ve used this to flatten in my configuration. Not using taliwind though.

config :esbuild,
  version: "0.17.18",
  default: [
    args: ~w(js/app.js --bundle --target=es2016,chrome58 --outdir=../priv/static/assets --external:*.woff2 --external:*.svg),
    cd: Path.expand("../assets", __DIR__),
    env: %{"NODE_PATH" => Path.expand("../deps", __DIR__)}
  ]