//run command npm install boostrap //go to app.js and Write import 'bootstrap/dist/css/bootstrap.css';import { Html, Head, Main, NextScript } from "next/document"; export default function Document() { return ( <Html> <Head> <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.0-beta1/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-giJF6kkoqNQ00vy+HMDP7azOuL0xtbfIcaT9wjKHr8RbDVddVHyTfAAsrekwKmP1" crossOrigin="anonymous" /> </Head> <body> <Main /> <NextScript /> </body> </Html> ); }