import Document, { Head } from 'next/document' import { DOMProperty } from 'react-dom/lib/ReactInjection' // By default React limit the set of valid DOM elements and attributes // (https://github.com/facebook/react/issues/140) this config whitelist // Amp elements/attributes DOMProperty.injectDOMPropertyConfig({ Properties: { amp: DOMProperty.MUST_USE_ATTRIBUTE }, isCustomAttribute: attributeName => attributeName.startsWith('amp-') }) export default class MyDocument extends Document { render () { const { html } = this.props return (