Nuxt/examples/with-firebase/nuxt.config.js

export default {
  head: {
    meta: [
      { charset: 'utf-8' },
      { name: 'viewport', content: 'width=device-width, initial-scale=1' }
    ],
    link: [
      { rel: 'stylesheet', href: 'https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css' }
    ]
  }
}