Parcel Bundler only loading boostrap on one page

Question

I'm trying to get the Parcel bundler to bundle my small static website that I'm building, so I can use npm packages etc. in my JS.

I've had several issues with it, but the sticking point seems to be using bootstrap, which only ever loads on one page.

I may be being incredibly dense here, but surely there must be a way to use NPM packages in your JS and bundle it up for live use.

Question: Why is bootstrap only loading on the contact.html page?

Sub-question: Is there a better alternative to packaging JS for use in static sites? (so I can use NPM packages)?

My file structure

My package.json file:

{
  "name": "parcel-test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "parcel index.html about.html contact.html",
    "build": "parcel build index.html about.html contact.html"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "node-sass": "^4.14.1",
    "parcel-bundler": "^1.12.4"
  },
  "dependencies": {
    "bootstrap": "^4.5.2",
    "jquery": "^3.5.1",
    "popper.js": "^1.16.1"
  }
}

main.js

import 'bootstrap';
import 'bootstrap/dist/css/bootstrap.css';