1npm install --save react-bootstrap
2npm install --save bootstrap

1import React from 'react';
2import '../path_to/bootstrap.min.css';
3
4const MyComponent = () => (
5    <div>
6        <p>This contains a button which uses the bootstrap.css</p>
7        <button class="btn btn-primary">Click me</button>
8    </div>
9);

1// npm i bootstrap jquery popper.js
2
3// On gatsby-browser.js
4import "bootstrap/dist/css/bootstrap.min.css";
5import "jquery/dist/jquery.min.js";
6import "popper.js/dist/popper.min";
7import "bootstrap/dist/js/bootstrap.min.js";

1import React from 'react';
2import { Button } from 'react-bootstrap';
3
4const MyComponent = () => (
5      <div>
6        <p>This contains a button which is exported by react-bootstrap</p>
7        <Button variant="primary">Primary</Button>
8    </div>
9);