You can easily include the components into your project by adding aurelia-ui-components
as a plugin in your app's main.js file.
To only load the components you're using, pass an array of component names when registering the plugin. For example: .plugin('aurelia-ui-components', ['menu', 'tooltip'])
The preferred way is by using SASS. Simply import components.scss into your app and all the component styles will be merged into your stylesheet.
There is also a precompiled CSS file in the dist/ folder you can use.
cd example; npm install
cd ..; npm run watch