feat: mobile responsiveness

react/src/components/Post.tsx

···
   const post = posts[parseInt(postId!)];
   return (
     <>
-      <div className="grid grid-cols-3 w-full">
+      <div className="md:grid md:grid-cols-3 flex flex-col w-full">
         <Link
           to="/"
-          className="text-gray-200 hover:text-gray-400 justify-self-start"
+          className="text-gray-200 hover:text-gray-400 flex justify-center items-center w-16"
         >
           Home
         </Link>
         <h2 className="text-3xl text-center">{post.title}</h2>
       </div>
-      <p className="text-lg w-[30%]">{post.content}</p>
+      <p className="text-lg md:w-3xl w-full">{post.content}</p>
     </>
   );
 }