fix tutorial examples

packages/flutter_widgets/example/lib/custom_theme.dart

@@ -41,11 +41,12 @@ class MyApp extends StatelessWidget {
   Widget build(BuildContext context) {
     final themeData = ThemeData(primarySwatch: Colors.green);
     final defaultTheme = StreamChatThemeData.fromTheme(themeData);
+    final colorTheme = defaultTheme.colorTheme;
     final customTheme = defaultTheme.merge(StreamChatThemeData(
       ownMessageTheme: MessageTheme(
-        messageBackgroundColor: StreamChatTheme.of(context).colorTheme.black,
+        messageBackgroundColor: colorTheme.black,
         messageText: TextStyle(
-          color: StreamChatTheme.of(context).colorTheme.white,
+          color: colorTheme.white,
         ),
         avatarTheme: AvatarTheme(
           borderRadius: BorderRadius.circular(8),

packages/flutter_widgets/example/lib/customize_channel_preview.dart

@@ -80,6 +80,17 @@ class ChannelListPage extends StatelessWidget {
     final opacity = channel.state.unreadCount > .0 ? 1.0 : 0.5;
 
     return ListTile(
+      onTap: () {
+        Navigator.push(
+          context,
+          MaterialPageRoute(
+            builder: (_) => StreamChannel(
+              child: ChannelPage(),
+              channel: channel,
+            ),
+          ),
+        );
+      },
       leading: ChannelImage(
         channel: channel,
       ),

packages/flutter_widgets/example/lib/customize_message_widget.dart

@@ -97,7 +97,7 @@ class ChannelPage extends StatelessWidget {
     List<Message> messages,
   ) {
     final message = details.message;
-    final color = details.isMyMessage ? Colors.blueGrey : Colors.blue;
+    final color = details.isMyMessage ? Colors.red : Colors.blue;
     if (message.isSystem) {
       return SizedBox();
     }
@@ -110,7 +110,10 @@ class ChannelPage extends StatelessWidget {
         color: color,
         width: 2,
       ),
-      padding: const EdgeInsets.all(2),
+      padding: const EdgeInsets.symmetric(
+        vertical: 2,
+        horizontal: 4,
+      ),
       attachmentBorderSide: BorderSide(
         color: color,
         width: 2,