chore: add prose css (#1133)

* chore: add prose css

* chore: comment out extra

Author: Tiffany Le-Nguyen

demos/default/components/Header.js

@@ -1,3 +1,3 @@
 export default function Header() {
-  return <h1>Next Demo!</h1>
+  return <h1>NextJS on Netlify (imported Header component)</h1>
 }

demos/default/pages/_app.js

@@ -1,7 +1,11 @@
 import '../styles/globals.css'
 
 function MyApp({ Component, pageProps }) {
-  return <Component {...pageProps} />
+  return (
+    <div className='prose ml-14 mt-10 mb-20'>
+      <Component {...pageProps} />
+    </div>
+  )
 }
 
 export default MyApp