Unable to upload taiwind CSS in React project

I am trying to use Tailwind CSS in the react project. I followed the steps given in the documentation from here. But after completing all the steps, I am unable to see the tailwind CSS changes. I am adding the styles in the file Home.js like this,

import React from "react";
    .
    .
    .

  return (
    <>
        <div className="bg-red-500 h-96 py-80">
        <h1 className="text-3xl font-bold underline bg-yellow-400">
      Hello world!
    </h1>
        </div>
    </>
  );
};

export default Home;

But it is not showing anything Following are the required files:

package.json

{
  "name": "authlogin-boilerplate",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@testing-library/jest-dom": "^5.11.4",
    "@testing-library/react": "^11.1.0",
    "@testing-library/user-event": "^12.1.10",
    "express": "^4.17.1",
    "react": "^17.0.2",
    "react-dom": "^17.0.2",
    "react-router-dom": "^6.1.1",
    "react-scripts": "4.0.3",
    "web-vitals": "^1.0.1"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": [
      "react-app",
      "react-app/jest"
    ]
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  },
  "devDependencies": {
    "autoprefixer": "^10.4.2",
    "postcss": "^8.4.5",
    "tailwindcss": "^3.0.11"
  }
}

tailwind.config.js

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

App.js

import { useState } from "react";
import "./App.css";
import "./index.css";
import Navbar from "./components/Navbar";
import Home from "./components/Home";
import About from "./components/About";
import SignupPage from "./components/SignupPage";
import LoginPage from "./components/LoginPage";
import ForgotPasswordPage from "./components/ForgotPasswordPage";
import ChangePasswordPage from "./components/ChangePasswordPage";
import Alert from "./components/Alert";

import { BrowserRouter as Router, Routes, Route } from "react-router-dom";

function App() {
  const [alert, setAlert] = useState(null);

  const showAlert = (message, type) => {
    setAlert({ msg: message, type: type });
    setTimeout(() => setAlert(null), 1500);
  };

  return (
    <>
      <Router>
        <Navbar showAlert={showAlert} />
        <Alert alert={alert} />
        <Routes>
          <Route path="/" element={<Home showAlert={showAlert} />} />
         .
         .
      </Router>
    </>
  );
}

export default App;

index.css

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

Also, my project structure is

On thing I noticed that in my index.css, I am getting this warning

I don't know the reason, I have restarted the laptop twice but not working.