design: Minor improvements

lib/pages/views/chat_list_view.dart

@@ -240,11 +240,17 @@ class ChatListView extends StatelessWidget {
                                               return Container();
                                             }
                                             return Material(
-                                              color: Colors.orange,
+                                              color: Theme.of(context)
+                                                  .secondaryHeaderColor,
                                               child: ListTile(
                                                 leading: CircleAvatar(
-                                                  backgroundColor: Colors.white,
-                                                  foregroundColor: Colors.black,
+                                                  backgroundColor: Theme.of(
+                                                          context)
+                                                      .scaffoldBackgroundColor,
+                                                  foregroundColor:
+                                                      Theme.of(context)
+                                                          .colorScheme
+                                                          .secondaryVariant,
                                                   child: Icon(Icons.cloud),
                                                 ),
                                                 trailing: IconButton(

lib/pages/views/chat_view.dart

@@ -270,12 +270,7 @@ class ChatView extends StatelessWidget {
                               (BuildContext context, int i) {
                                 return i == controller.filteredEvents.length + 1
                                     ? controller.timeline.isRequestingHistory
-                                        ? Container(
-                                            height: 50,
-                                            alignment: Alignment.center,
-                                            padding: EdgeInsets.all(8),
-                                            child: CircularProgressIndicator(),
-                                          )
+                                        ? LinearProgressIndicator()
                                         : controller.canLoadMore
                                             ? Center(
                                               child: OutlinedButton(