[site/pages,#170][s]: create new 404 page

site/pages/404.jsx

@@ -0,0 +1,18 @@
+import Link from "next/link"
+
+export default function PageNotFound () {
+  return (
+    <section className="flex items-center h-full p-16 text-primary lg:max-h-[calc(100vh-350px)]">
+      <div className="container flex flex-col items-center justify-center px-5 mx-auto my-8">
+        <div className="max-w-md text-center">
+          <h2 className="mb-4 font-extrabold text-7xl md:text-9xl">
+            <span className="sr-only">Error</span>404
+          </h2>
+          <p className="text-2xl font-semibold md:text-3xl">Sorry, we couldn't find this page.</p>
+          <p className="mt-2 mb-8 text-gray-500">But dont worry, you can find plenty of other things on our homepage.</p>
+          <Link href="/" className="px-8 py-3 font-semibold rounded bg-secondary">Back to homepage</Link>
+        </div>
+      </div>
+    </section>
+  )
+}