//1.run following commnad in cmd:
npm install bootstrap --save
//you can now use bootstrap component. example:
import { Button } from 'react-bootstrap';
//2.or add this to index.js:
<link
rel="stylesheet"
href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.0/dist/css/bootstrap.min.css"
integrity="sha384-B0vP5xmATw1+K9KRQjQERJvTumQW0nPEzvF6L/Z6nronJ3oUOFUFpCjEUQouq2+l"
crossorigin="anonymous"
/>