Merge pull request #1089 from GetStream/fix/overlapping_chat_docs

doc(repo): Fixed code in the overlapping chat with transparency docs

docusaurus/docs/Flutter/guides/adding_chat_to_video_livestreams.mdx

@@ -64,30 +64,34 @@ The second type looks like this:
 We can use a `Stack` for achieving this:
 
 ```dart
-Scaffold(
+Stack(
-  body: Stack(
+  children: <Widget>[
-    children: <Widget>[
+    // Add your video implementation here
-      // Add your video implementation here
+    ShaderMask(
-      ShaderMask(
+      shaderCallback: (rect) {
-        shaderCallback: (rect) {
+        return const LinearGradient(
-          return LinearGradient(
             begin: Alignment.bottomCenter,
             end: Alignment.topCenter,
-           colors: [Colors.black, Colors.transparent],
+            colors: [Colors.black, Colors.transparent],
-           stops: [0.4, 0.65]
+            stops: [0.4, 0.8]).createShader(
-          ).createShader(Rect.fromLTRB(0, 0, rect.width, rect.height));
+          Rect.fromLTRB(0, 0, rect.width, rect.height),
-        },
+        );
-       blendMode: BlendMode.dstIn,
+      },
-         child: Column(
+      blendMode: BlendMode.dstIn,
-           children: [
+      child: Column(
-             Expanded(
+        children: const [
-               child: MessageListView(),
+          Expanded(
-             ),
+            child: MessageListViewTheme(
-             MessageInput(),
+              data: MessageListViewThemeData(
-           ],
+                backgroundColor: Colors.transparent,
-         ),
+              ),
-       ),
+              child: MessageListView(),
-     ],
+            ),
-   ),
+          ),
- )
+          MessageInput(),
+        ],
+      ),
+    ),
+  ],
+),
 ```