next.js/examples/with-flow/pages/_app.js

import App, {Container} from 'next/app'
import Link from 'next/link'
import React from 'react'

export default class MyApp extends App {
  static async getInitialProps ({ Component, router, ctx }) {
    let pageProps = {}

    if (Component.getInitialProps) {
      pageProps = await Component.getInitialProps(ctx)
    }

    return {pageProps}
  }

  render () {
    const {Component, pageProps} = this.props
    return (
      <Container>
        <header>
          <nav>
            <Link href='/'><a>Home</a></Link>|
            <Link href='/about'><a>About</a></Link>|
            <Link href='/contact'><a>Contact</a></Link>
          </nav>
        </header>

        <Component {...pageProps} />

        <footer>
          I`m here to stay
        </footer>
      </Container>
    )
  }
}