The warning on terminal:

npm run dev

> app-name@0.1.0 dev
> next dev

  â–² Next.js 13.5.6
  - Local:        http://localhost:3000

 ✓ Ready in 3.1s

warn - No utility classes were detected in your source files. If this is unexpected, double-check the `content` option in your Tailwind CSS configuration.
warn - https://tailwindcss.com/docs/content-configuration

Tailwind.config.js file :

import type { Config } from 'tailwindcss'

const config: Config = {
  content: [
    './pages/**/*.{js,ts,jsx,tsx,mdx}',
    './components/**/*.{js,ts,jsx,tsx,mdx}',
    './app/**/*.{js,ts,jsx,tsx,mdx}',
  ],
  theme: {
    extend: {
      backgroundImage: {
        'gradient-radial': 'radial-gradient(var(--tw-gradient-stops))',
        'gradient-conic':
          'conic-gradient(from 180deg at 50% 50%, var(--tw-gradient-stops))',
      },
    },
  },
  plugins: [],
}
export default config

Global.css file :

@tailwind base;
@tailwind components;
@tailwind utilities;

:root {
  --foreground-rgb: 0, 0, 0;
  --background-start-rgb: 214, 219, 220;
  --background-end-rgb: 255, 255, 255;
}

@media (prefers-color-scheme: dark) {
  :root {
    --foreground-rgb: 255, 255, 255;
    --background-start-rgb: 0, 0, 0;
    --background-end-rgb: 0, 0, 0;
  }
}

body {
  color: rgb(var(--foreground-rgb));
  background: linear-gradient(
      to bottom,
      transparent,
      rgb(var(--background-end-rgb))
    )
    rgb(var(--background-start-rgb));
}

It's a new project, with all standard configs by the Create Next App CLI. Where am I going wrong?
Thanks!