fix: 桌面端深色模式详情页卡片的一个错误

Author: MiaoMint

lib/widgets/card_tile.dart

@@ -44,7 +44,9 @@ class CardTile extends StatelessWidget {
             decoration: BoxDecoration(
               border: Border(
                 bottom: BorderSide(
-                  color: Colors.grey.withOpacity(0.1),
+                  color: FluentTheme.of(context).brightness == Brightness.dark
+                      ? Colors.white.withOpacity(0.1)
+                      : Colors.grey.withOpacity(0.1),
                   width: 1,
                 ),
               ),