refactor tailwind typography to v3 and update styling

layouts/PostLayout.tsx

@@ -92,7 +92,7 @@ export default function PostLayout({ content, authorDetails, next, prev, childre
               </dd>
             </dl>
             <div className="divide-y divide-gray-200 dark:divide-gray-700 xl:col-span-3 xl:row-span-2 xl:pb-0">
-              <div className="prose max-w-none pb-8 pt-10 dark:prose-dark">{children}</div>
+              <div className="prose max-w-none pb-8 pt-10 dark:prose-invert">{children}</div>
               <div className="pb-6 pt-6 text-sm text-gray-700 dark:text-gray-300">
                 <Link href={discussUrl(path)} rel="nofollow">
                   Discuss on Twitter
@@ -125,7 +125,7 @@ export default function PostLayout({ content, authorDetails, next, prev, childre
                 )}
                 {(next || prev) && (
                   <div className="flex justify-between py-4 xl:block xl:space-y-8 xl:py-8">
-                    {prev && (
+                    {prev && prev.path && (
                       <div>
                         <h2 className="text-xs uppercase tracking-wide text-gray-500 dark:text-gray-400">
                           Previous Article
@@ -135,7 +135,7 @@ export default function PostLayout({ content, authorDetails, next, prev, childre
                         </div>
                       </div>
                     )}
-                    {next && (
+                    {next && next.path && (
                       <div>
                         <h2 className="text-xs uppercase tracking-wide text-gray-500 dark:text-gray-400">
                           Next Article