fix: adjusted size of headers for 404

Author: arcticnoah

themes/hello-friend/layouts/404.html

@@ -2,8 +2,8 @@
 {{ define "main"}}
 <main id="main">
   <div>
-    <h3 id="title">404 - Page not found</h3>
-    <h6 id="title"><a href="{{ "/" | relURL }}">Go Home</a></h6>
+    <h2 id="title">404 - Page not found</h2>
+    <h4 id="title"><a href="{{ "/" | relURL }}">Go Home</a></h4>
   </div>
 </main>
 {{ end }}