Some CSS-in-JS tools allows us to collect the page's styles while server-side rendering the page to HTML.

This enables us to add the styles to the HTML so that the browser loads the styles before loading the JavaScript.

// renderer/_default.page.server.jsx

import ReactDOMServer from "react-dom/server";
import React from "react";
import { escapeInject, dangerouslySkipEscape } from "vite-plugin-ssr";
import { CssCollector } from 'some-css-in-js-tool'

export { render };

function render(pageContext) {
  const { Page } = pageContext;
  const page = <Page />;

  const collect = new CssCollector()

  const pageHtml = ReactDOMServer.renderToString(collect(page));

  // `vite-plugin-ssr` inserts the `<script>` tags at the end of the HTML; the
  // browser will load the `<style>` tag first.
  return escapeInject`<!DOCTYPE html>
        <div id="page-view">${dangerouslySkipEscape(pageHtml)}</div>