Just install the lib and import the css files in [vendor.ts](https://github.com/preboot/angular2-webpack/blob/master/src/vendor.ts). For example this is how to do it with bootstrap:
npm install optum-global-navigatorsh
npm install bootstrap@next --save
`
And in vendor.ts add the following:
`ts
import 'bootstrap/dist/css/bootstrap.css';
``