chore: Pinned events design

lib/pages/chat/pinned_events.dart

@@ -66,9 +66,7 @@ class PinnedEvents extends StatelessWidget {
 
           final fontSize = AppConfig.messageFontSize * AppConfig.fontSizeFactor;
           return Material(
-            color: Theme.of(context).appBarTheme.backgroundColor,
-            elevation: Theme.of(context).appBarTheme.elevation ?? 10,
-            shadowColor: Theme.of(context).appBarTheme.shadowColor,
+            color: Theme.of(context).colorScheme.surfaceVariant,
             child: InkWell(
               onTap: () => _displayPinnedEventsDialog(
                 context,
@@ -79,6 +77,7 @@ class PinnedEvents extends StatelessWidget {
                   IconButton(
                     splashRadius: 20,
                     iconSize: 20,
+                    color: Theme.of(context).colorScheme.onSurfaceVariant,
                     icon: const Icon(Icons.push_pin),
                     tooltip: L10n.of(context)!.unpin,
                     onPressed: controller.room
@@ -106,6 +105,9 @@ class PinnedEvents extends StatelessWidget {
                                   ),
                               maxLines: 2,
                               textStyle: TextStyle(
+                                color: Theme.of(context)
+                                    .colorScheme
+                                    .onSurfaceVariant,
                                 overflow: TextOverflow.ellipsis,
                                 fontSize: fontSize,
                                 decoration: event.redacted
@@ -114,10 +116,8 @@ class PinnedEvents extends StatelessWidget {
                               ),
                               linkStyle: TextStyle(
                                 color: Theme.of(context)
-                                    .textTheme
-                                    .bodyText1
-                                    ?.color
-                                    ?.withAlpha(150),
+                                    .colorScheme
+                                    .onSurfaceVariant,
                                 fontSize: fontSize,
                                 decoration: TextDecoration.underline,
                               ),

lib/pages/chat/tombstone_display.dart

@@ -17,12 +17,12 @@ class TombstoneDisplay extends StatelessWidget {
     return SizedBox(
       height: 72,
       child: Material(
-        color: Theme.of(context).secondaryHeaderColor,
+        color: Theme.of(context).colorScheme.surfaceVariant,
         elevation: 1,
         child: ListTile(
           leading: CircleAvatar(
-            foregroundColor: Theme.of(context).colorScheme.secondary,
-            backgroundColor: Theme.of(context).backgroundColor,
+            foregroundColor: Theme.of(context).colorScheme.onSecondary,
+            backgroundColor: Theme.of(context).colorScheme.secondary,
             child: const Icon(Icons.upgrade_outlined),
           ),
           title: Text(
@@ -32,6 +32,9 @@ class TombstoneDisplay extends StatelessWidget {
                 .body,
             maxLines: 1,
             overflow: TextOverflow.ellipsis,
+            style: TextStyle(
+              color: Theme.of(context).colorScheme.onSurfaceVariant,
+            ),
           ),
           subtitle: Text(L10n.of(context)!.goToTheNewRoom),
           onTap: controller.goToNewRoomAction,