Making it work for ESP32

vite.config.ts

@@ -1,9 +1,62 @@
 import { sveltekit } from '@sveltejs/kit/vite';
 import { defineConfig } from 'vite';
 
+import * as fs from 'fs'
+import * as path from 'path'
+
+const doRewrap = ({ cssClass }) => {
+	try {
+		if (fs.existsSync(path.resolve(__dirname, 'dist/bundle.js'))) {
+			return
+		}
+	} catch(e) {}
+	console.log("\nStart re-wrapping...")
+	fs.readFile(path.resolve(__dirname, 'dist/bundle.html'), 'utf8', function(err, data){
+		if (!data) {
+			console.log(`[Error]: No bundle.html generated, check svelte.config.js -> config.kit.adapter -> fallback: "bundle.html"`)
+			return
+		}
+		let matchData = data.match(/(?<=<script\b[^>]*>)([\s\S]*?)(?=<\/script>)/gm)
+		if (matchData) {
+			let cleanData = matchData[0].trim()
+				.replace(`document.querySelector('[data-sveltekit-hydrate="45h"]').parentNode`, `document.querySelector(".${cssClass}")`)
+			fs.writeFile(path.resolve(__dirname, 'dist/bundle.js'), cleanData, (err) => {
+				if (err)
+					console.log(err)
+				else {
+					try {
+						fs.rename(path.resolve(__dirname,'dist/index.page'), path.resolve(__dirname, 'dist/index.html'), (err) => { })
+					} catch (e) { }
+					try {
+						fs.unlinkSync(path.resolve(__dirname, 'dist/bundle.html'))
+					} catch (e) { }
+					console.log("Finished: bundle.js + index.html have been regenerated.\n")
+				}
+			})
+		} else 
+			console.log(`[Error]: No proper <script> tag found in bundle.html`)
+	})
+}
+
+
 export default defineConfig({
-	plugins: [sveltekit()],
+	plugins: [sveltekit(), {
+		name: 'postbuild-command', 
+			closeBundle: {
+				order: 'post',
+				handler() {
+					setTimeout(() => doRewrap({ cssClass: "overlay" }), Math.random()*500+500)
+				}
+			}
+	}],
 	build: {
-		minify: true
+		minify: true,
+		cssCodeSplit: false,
+		rollupOptions: {
+			output: {
+				manualChunks: () => 'app',
+				assetFileNames: "[name][extname]"
+			}
+		}
 	}
 });