TailwindCSS's output file is empty after using the build command

Question

I tried using TailwindCSS on MacOS. I installed it with the following command:

npm install -D tailwindcss

Then to create the configuration file, I ran the following command:

npx tailwindcss init

Then I configured my configuration file (tailwind.config.js) to the following code:

module.exports = {
  content: ["./src/**/*.{html,js}"],
  theme: {
    extend: {},
  },
  plugins: [],
}

After adding a few files my explorer looks like this:

Finally, I ran the following command expecting some CSS to appear in my output.css file:

npx tailwindcss -i ./src/input.css -o ./dist/output.css --watch

I checked my output.css file and it was empty. By the way, in my input.css file I entered the following lines of code:

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

However after running the previous command saw see the following messages in my terminal:

warn - The `content` option in your Tailwind CSS configuration is missing or empty.
warn - Configure your content sources or your generated CSS will be missing styles.
warn - https://tailwindcss.com/docs/content-configuration

Does anyone know why this is not working?