I would like to add a bootstrap add-on, namely [Bootstrap Toggle](http://www.bootstraptoggle.com/) to a JHipster Project. The project consists of a `.css` and `.js` file and requires jquery. 

Simply adding this to `index.html` works fine but feels hacky. 

```
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<link href="https://gitcdn.github.io/bootstrap-toggle/2.2.2/css/bootstrap-toggle.min.css" rel="stylesheet">
<script src="https://gitcdn.github.io/bootstrap-toggle/2.2.2/js/bootstrap-toggle.min.js"></script>

```

I would like to take advantage of yarn and webpack. I tried adding a `vendor.css` to the content folder which imports the toggle css file, but that didn't seem to do anything: 

```
@import 'node_modules/boostrap-toggle/css/bootstrap-toggle.css';

```

How can I add Bootstrap Toggle (or similar libraries) from my `node_modules` folder to the application?