emotion/app/entry.server.tsx

import { CacheProvider } from "@emotion/react";
import createEmotionServer from "@emotion/server/create-instance";
import type { AppLoadContext, EntryContext } from "@remix-run/node";
import { RemixServer } from "@remix-run/react";
import { renderToString } from "react-dom/server";

import createEmotionCache from "~/styles/createEmotionCache";
import ServerStyleContext from "~/styles/server.context";

export default function handleRequest(
  request: Request,
  responseStatusCode: number,
  responseHeaders: Headers,
  remixContext: EntryContext,
  loadContext: AppLoadContext,
) {
  const cache = createEmotionCache();
  const { extractCriticalToChunks } = createEmotionServer(cache);

  const html = renderToString(
    <ServerStyleContext.Provider value={null}>
      <CacheProvider value={cache}>
        <RemixServer context={remixContext} url={request.url} />
      </CacheProvider>
    </ServerStyleContext.Provider>,
  );

  const chunks = extractCriticalToChunks(html);

  const markup = renderToString(
    <ServerStyleContext.Provider value={chunks.styles}>
      <CacheProvider value={cache}>
        <RemixServer context={remixContext} url={request.url} />
      </CacheProvider>
    </ServerStyleContext.Provider>,
  );

  responseHeaders.set("Content-Type", "text/html");

  return new Response(`<!DOCTYPE html>${markup}`, {
    status: responseStatusCode,
    headers: responseHeaders,
  });
}