[cdn] fixing minor page rendering issues (#1392)

### Description
Fixing minor page rendering issues

### Type of Change

- [ ] New Example
- [x] Example updates (Bug fixes, new features, etc.)
- [ ] Other (changes to the codebase, but not to examples)

### New Example Checklist

- [ ] 🛫 `npm run new-example` was used to create the example
- [ ] 📚 The template wasn't used but I carefuly read the [Adding a new
example](https://github.com/vercel/examples#adding-a-new-example) steps
and implemented them in the example
- [ ] 📱 Is it responsive? Are mobile and tablets considered?

Author: raochand

cdn/custom-error-pages-app-dir/app/globals.css

@@ -22,5 +22,5 @@
 body {
   background: var(--background);
   color: var(--foreground);
-  font-family: Arial, Helvetica, sans-serif;
+  font-family: var(--font-geist-sans), Arial, Helvetica, sans-serif;
 }

cdn/custom-error-pages-app-dir/app/layout.tsx

@@ -5,11 +5,13 @@ import "./globals.css";
 const geistSans = Geist({
   variable: "--font-geist-sans",
   subsets: ["latin"],
+  adjustFontFallback: true,
 });
 
 const geistMono = Geist_Mono({
   variable: "--font-geist-mono",
   subsets: ["latin"],
+  adjustFontFallback: true,
 });
 
 export const metadata: Metadata = {

cdn/custom-error-pages-app-dir/app/page.tsx

@@ -2,7 +2,7 @@ import Image from "next/image";
 
 export default function Home() {
   return (
-    <div className="flex min-h-screen items-center justify-center bg-zinc-50 font-sans dark:bg-black">
+    <div className="flex min-h-screen justify-center bg-zinc-50 dark:bg-black">
       <main className="flex w-full max-w-3xl flex-col items-center gap-8 py-12 px-8 bg-white dark:bg-black sm:items-start sm:px-16">
         <Image
           className="dark:invert"

cdn/custom-error-pages-public-dir/app/globals.css

@@ -22,5 +22,5 @@
 body {
   background: var(--background);
   color: var(--foreground);
-  font-family: Arial, Helvetica, sans-serif;
+  font-family: var(--font-geist-sans), Arial, Helvetica, sans-serif;
 }

cdn/custom-error-pages-public-dir/app/layout.tsx

@@ -5,11 +5,13 @@ import "./globals.css";
 const geistSans = Geist({
   variable: "--font-geist-sans",
   subsets: ["latin"],
+  adjustFontFallback: true,
 });
 
 const geistMono = Geist_Mono({
   variable: "--font-geist-mono",
   subsets: ["latin"],
+  adjustFontFallback: true,
 });
 
 export const metadata: Metadata = {

cdn/custom-error-pages-public-dir/app/page.tsx

@@ -2,7 +2,7 @@ import Image from "next/image";
 
 export default function Home() {
   return (
-    <div className="flex min-h-screen items-center justify-center bg-zinc-50 font-sans dark:bg-black">
+    <div className="flex min-h-screen justify-center bg-zinc-50 dark:bg-black">
       <main className="flex w-full max-w-3xl flex-col items-center gap-8 py-12 px-8 bg-white dark:bg-black sm:items-start sm:px-16">
         <Image
           className="dark:invert"