pages/_document.tsx

// pages/_document.js
import Document, {
  Head,
  Html,
  Main,
  NextScript,
} from 'next/document'
import { ServerStyleSheet } from 'styled-components'

class MyDocument extends Document {
  static async getInitialProps(ctx) {
    const sheet = new ServerStyleSheet()
    const originalRenderPage = ctx.renderPage

    try {
      ctx.renderPage = () => originalRenderPage({
        enhanceApp: App => props => sheet.collectStyles(<App {...props} />),
      })

      const initialProps = await Document.getInitialProps(ctx)

      return {
        ...initialProps,
        styles: [initialProps.styles, sheet.getStyleElement()],
      }
    }
    finally {
      sheet.seal()
    }
  }

  render() {
    return (
      <Html data-theme="dark">
        <Head>
          <link
            href="https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&display=swap"
            rel="stylesheet"
          />
          <link
            rel="stylesheet"
            href="https://cdn.jsdelivr.net/npm/@docsearch/css@3"
          />
        </Head>
        <body>
          <Main />
          <NextScript />
        </body>
      </Html>
    )
  }
}

export default MyDocument