update theme

lib/features/cart/presentation/widgets/price_negotiation_section.dart

@@ -18,6 +18,8 @@ class PriceNegotiationSection extends HookWidget {
 
   @override
   Widget build(BuildContext context) {
+    final colorScheme = Theme.of(context).colorScheme;
+
     return Container(
       margin: const EdgeInsets.symmetric(horizontal: AppSpacing.md),
       padding: const EdgeInsets.all(AppSpacing.md),
@@ -35,7 +37,7 @@ class PriceNegotiationSection extends HookWidget {
             },
             activeColor: AppColors.warning,
           ),
-          const Expanded(
+          Expanded(
             child: Column(
               crossAxisAlignment: CrossAxisAlignment.start,
               children: [
@@ -44,13 +46,16 @@ class PriceNegotiationSection extends HookWidget {
                   style: TextStyle(
                     fontSize: 15,
                     fontWeight: FontWeight.w600,
-                    color: Color(0xFF212121),
+                    color: colorScheme.onSurface,
                   ),
                 ),
-                SizedBox(height: 4),
+                const SizedBox(height: 4),
                 Text(
                   'Gửi yêu cầu đàm phán giá cho đơn hàng này',
-                  style: TextStyle(fontSize: 13, color: AppColors.grey500),
+                  style: TextStyle(
+                    fontSize: 13,
+                    color: colorScheme.onSurfaceVariant,
+                  ),
                 ),
               ],
             ),