💄 Optimize post detail layout

lib/screens/posts/post_detail.dart

@@ -459,13 +459,12 @@ class _PostDetailLargeScreenLayout extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final user = ref.watch(userInfoProvider);
+
     return Row(
       children: [
         Expanded(
           flex: 3,
-          child: Material(
-            color: Theme.of(context).cardTheme.color,
-            elevation: 8,
           child: Center(
             child: Padding(
               padding: const EdgeInsets.all(24),
@@ -477,9 +476,14 @@ class _PostDetailLargeScreenLayout extends StatelessWidget {
             ),
           ),
         ),
-        ),
         Expanded(
           flex: 2,
+          child: Stack(
+            fit: StackFit.expand,
+            children: [
+              Material(
+                color: Theme.of(context).colorScheme.surfaceContainer,
+                elevation: 8,
                 child: CustomScrollView(
                   slivers: [
                     SliverToBoxAdapter(
@@ -519,6 +523,24 @@ class _PostDetailLargeScreenLayout extends StatelessWidget {
                   ],
                 ),
               ),
+              if (user.value != null)
+                Positioned(
+                  bottom: 16 + MediaQuery.of(context).padding.bottom,
+                  left: 16,
+                  right: 16,
+                  child: ConstrainedBox(
+                    constraints: BoxConstraints(maxWidth: 800),
+                    child: PostQuickReply(
+                      parent: post,
+                      onPosted: () {
+                        ref.read(postRepliesProvider(postId).notifier).refresh();
+                      },
+                    ),
+                  ).center(),
+                ),
+            ],
+          ),
+        ),
       ],
     );
   }