Here is how to install tailwind version 4 with a flask app that has blueprints.

The tailwind.config,js might vary if you are not using blueprints in flask.

Here are the instructions in flask

https://tailwindcss.com/docs/installation/tailwind-cli

First I run > npm init -y

package.json

{

 "name":"someapp",

 "version":"1.0.0",

 "description":"1. Clone the project",

 "main":"index.js",

 "scripts": {

 "tailwind-build":"npx tailwindcss -i ./app/static/src/input.css -o ./app/static/output.css --watch --config C:/Users/user/OneDrive/Desktop/someapp/tailwind.config.js"

   },

 "keywords": \[\],

 "author":"",

 "license":"ISC",

 "dependencies": {

   "@tailwindcss/cli":"\^4.0.13",

   "tailwindcss":"\^4.0.13"

 }

}

Next

> \npm install tailwindcssu/tailwindcss/cli``

Then I manually create input.css in the src folder

static/src/input.css

Here are the contents of *input.css*

 "tailwindcss";

Then I manually create tailwind.config,js in someapp folder

Here are the contents of *tailwind.config,js*

/**  {import('tailwindcss').Config} */
export default {
    content: ["./app/templates/**/*.html", "./app/static/src/**/*.css"],
    theme: {
      extend: {},
    },
    plugins: [],
  };

Then if you are using vscode type in the terminal > run npm run tailwind-build and then on a second terminal I open go flask run/ run the flask code. ALso make sure both terminals are open at the same time and both running.

I have no idea how this works in production though.

I based the flask app on a similar structure to this https://github.com/miguelgrinberg/microblog

Also make sure you point to the static folder or whatever the name is.

app = Flask(__name__, static_folder='static')