diff --git a/lib/app/app_shell.dart b/lib/app/app_shell.dart
index 1df58450..a9ad95f9 100644
--- a/lib/app/app_shell.dart
+++ b/lib/app/app_shell.dart
@@ -57,6 +57,7 @@ class _AppShellState extends State<AppShell> {
         final controller = widget.controller;
         return Scaffold(
           body: SafeArea(
+            bottom: false,
             child: LayoutBuilder(
               builder: (context, constraints) {
                 final palette = context.palette;
diff --git a/lib/features/account/account_page.dart b/lib/features/account/account_page.dart
index 4488b56a..eda89d0c 100644
--- a/lib/features/account/account_page.dart
+++ b/lib/features/account/account_page.dart
@@ -28,7 +28,7 @@ class _AccountPageState extends State<AccountPage> {
       animation: controller,
       builder: (context, _) {
         return SingleChildScrollView(
-          padding: const EdgeInsets.fromLTRB(32, 32, 32, 16),
+          padding: const EdgeInsets.fromLTRB(32, 32, 32, 8),
           child: Column(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
diff --git a/lib/features/assistant/assistant_page.dart b/lib/features/assistant/assistant_page.dart
index 2a9f57f2..2252c014 100644
--- a/lib/features/assistant/assistant_page.dart
+++ b/lib/features/assistant/assistant_page.dart
@@ -10,6 +10,7 @@ import '../../i18n/app_language.dart';
 import '../../models/app_models.dart';
 import '../../runtime/runtime_models.dart';
 import '../../theme/app_palette.dart';
+import '../../theme/app_theme.dart';
 import '../../widgets/gateway_connect_dialog.dart';
 import '../../widgets/pane_resize_handle.dart';
 import '../../widgets/surface_card.dart';
@@ -37,7 +38,7 @@ class _AssistantPageState extends State<AssistantPage> {
   late final FocusNode _composerFocusNode;
   String _mode = 'ask';
   String _thinkingLabel = 'high';
-  double _conversationPaneRatio = 0.64;
+  double _conversationPaneRatio = 0.7;
   List<_ComposerAttachment> _attachments = const <_ComposerAttachment>[];
   String? _lastSubmittedPrompt;
   String? _lastAutoAgentLabel;
@@ -80,21 +81,21 @@ class _AssistantPageState extends State<AssistantPage> {
         });
 
         return Padding(
-          padding: const EdgeInsets.fromLTRB(8, 8, 8, 8),
+          padding: const EdgeInsets.fromLTRB(6, 6, 6, 6),
           child: LayoutBuilder(
             builder: (context, constraints) {
-              const handleHeight = 12.0;
-              const paneGap = 8.0;
+              const handleHeight = 10.0;
+              const paneGap = 6.0;
               final availablePaneHeight =
                   (constraints.maxHeight - handleHeight - paneGap)
                       .clamp(0.0, double.infinity)
                       .toDouble();
               var minConversationHeight = availablePaneHeight >= 620
-                  ? 220.0
-                  : availablePaneHeight * 0.34;
+                  ? 240.0
+                  : availablePaneHeight * 0.4;
               var minComposerHeight = availablePaneHeight >= 620
-                  ? 248.0
-                  : availablePaneHeight * 0.30;
+                  ? 176.0
+                  : availablePaneHeight * 0.24;
               if (minConversationHeight + minComposerHeight >
                   availablePaneHeight) {
                 minConversationHeight = availablePaneHeight * 0.52;
@@ -578,12 +579,12 @@ class _ConversationArea extends StatelessWidget {
     final theme = Theme.of(context);
 
     return SurfaceCard(
-      borderRadius: 14,
+      borderRadius: 12,
       padding: EdgeInsets.zero,
       child: Column(
         children: [
           Padding(
-            padding: const EdgeInsets.fromLTRB(16, 12, 16, 10),
+            padding: const EdgeInsets.fromLTRB(14, 10, 14, 8),
             child: Row(
               children: [
                 Expanded(
@@ -594,7 +595,7 @@ class _ConversationArea extends StatelessWidget {
                         controller.currentSessionKey,
                         style: theme.textTheme.titleLarge,
                       ),
-                      const SizedBox(height: 2),
+                      const SizedBox(height: 4),
                       Text(
                         controller.connection.status ==
                                 RuntimeConnectionStatus.connected
@@ -628,10 +629,10 @@ class _ConversationArea extends StatelessWidget {
                     )
                   : ListView.separated(
                       controller: scrollController,
-                      padding: const EdgeInsets.fromLTRB(18, 16, 18, 16),
+                      padding: const EdgeInsets.fromLTRB(14, 12, 14, 12),
                       physics: const BouncingScrollPhysics(),
                       itemCount: items.length,
-                      separatorBuilder: (_, _) => const SizedBox(height: 10),
+                      separatorBuilder: (_, _) => const SizedBox(height: 8),
                       itemBuilder: (context, index) {
                         final item = items[index];
                         return switch (item.kind) {
@@ -796,22 +797,22 @@ class _AssistantEmptyState extends StatelessWidget {
 
     return Center(
       child: ConstrainedBox(
-        constraints: const BoxConstraints(maxWidth: 520),
+        constraints: const BoxConstraints(maxWidth: 500),
         child: Padding(
-          padding: const EdgeInsets.all(24),
+          padding: const EdgeInsets.all(16),
           child: SurfaceCard(
-            borderRadius: 20,
+            borderRadius: 12,
             child: Column(
               mainAxisSize: MainAxisSize.min,
               crossAxisAlignment: CrossAxisAlignment.start,
               children: [
                 Text(title, style: theme.textTheme.headlineSmall),
-                const SizedBox(height: 10),
+                const SizedBox(height: 8),
                 Text(description, style: theme.textTheme.bodyMedium),
-                const SizedBox(height: 18),
+                const SizedBox(height: 12),
                 Wrap(
-                  spacing: 12,
-                  runSpacing: 12,
+                  spacing: 8,
+                  runSpacing: 8,
                   children: [
                     FilledButton.icon(
                       onPressed: connected
@@ -925,7 +926,7 @@ class _ComposerBar extends StatelessWidget {
         : appText('连接', 'Connect');
 
     return SurfaceCard(
-      borderRadius: 16,
+      borderRadius: 12,
       child: Column(
         crossAxisAlignment: CrossAxisAlignment.start,
         children: [
@@ -936,21 +937,21 @@ class _ComposerBar extends StatelessWidget {
               children: attachments
                   .map(
                     (attachment) => InputChip(
-                      avatar: Icon(attachment.icon, size: 18),
+                      avatar: Icon(attachment.icon, size: 16),
                       label: Text(attachment.name),
                       onDeleted: () => onRemoveAttachment(attachment),
                     ),
                   )
                   .toList(),
             ),
-            const SizedBox(height: 10),
+            const SizedBox(height: 8),
           ],
           TextField(
             controller: inputController,
             focusNode: focusNode,
             autofocus: true,
-            minLines: 4,
-            maxLines: 8,
+            minLines: 2,
+            maxLines: 6,
             decoration: InputDecoration(
               border: InputBorder.none,
               isCollapsed: true,
@@ -961,7 +962,7 @@ class _ComposerBar extends StatelessWidget {
             ),
             onSubmitted: (_) => onSend(),
           ),
-          const SizedBox(height: 12),
+          const SizedBox(height: 8),
           Row(
             children: [
               Expanded(
@@ -1225,12 +1226,12 @@ class _ComposerBar extends StatelessWidget {
                       : onOpenGateway,
                   style: FilledButton.styleFrom(
                     padding: const EdgeInsets.symmetric(
-                      horizontal: 14,
-                      vertical: 10,
+                      horizontal: 12,
+                      vertical: 8,
                     ),
-                    minimumSize: const Size(92, 40),
+                    minimumSize: const Size(80, 34),
                     shape: RoundedRectangleBorder(
-                      borderRadius: BorderRadius.circular(999),
+                      borderRadius: BorderRadius.circular(8),
                     ),
                   ),
                   child: Row(
@@ -1268,14 +1269,14 @@ class _ComposerIconButton extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return Container(
-      width: 36,
-      height: 36,
+      width: 32,
+      height: 32,
       decoration: BoxDecoration(
         color: context.palette.surfaceSecondary,
-        borderRadius: BorderRadius.circular(10),
+        borderRadius: BorderRadius.circular(8),
         border: Border.all(color: context.palette.strokeSoft),
       ),
-      child: Icon(icon, size: 18, color: context.palette.textMuted),
+      child: Icon(icon, size: 16, color: context.palette.textMuted),
     );
   }
 }
@@ -1305,16 +1306,16 @@ class _ComposerToolbarChip extends StatelessWidget {
     final palette = context.palette;
 
     return Container(
-      padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 8),
+      padding: const EdgeInsets.symmetric(horizontal: AppSpacing.xs, vertical: 6),
       decoration: BoxDecoration(
         color: backgroundColor ?? palette.surfaceSecondary,
-        borderRadius: BorderRadius.circular(999),
+        borderRadius: BorderRadius.circular(AppRadius.chip),
         border: Border.all(color: borderColor ?? palette.strokeSoft),
       ),
       child: Row(
         mainAxisSize: MainAxisSize.min,
         children: [
-          Icon(icon, size: 15, color: foregroundColor ?? palette.textMuted),
+          Icon(icon, size: 14, color: foregroundColor ?? palette.textMuted),
           const SizedBox(width: 6),
           ConstrainedBox(
             constraints: BoxConstraints(maxWidth: maxLabelWidth),
@@ -1328,10 +1329,10 @@ class _ComposerToolbarChip extends StatelessWidget {
             ),
           ),
           if (showChevron) ...[
-            const SizedBox(width: 4),
+            const SizedBox(width: 2),
             Icon(
               Icons.keyboard_arrow_down_rounded,
-              size: 16,
+              size: 14,
               color: foregroundColor ?? palette.textMuted,
             ),
           ],
@@ -1369,29 +1370,22 @@ class _MessageBubble extends StatelessWidget {
       child: ConstrainedBox(
         constraints: const BoxConstraints(maxWidth: 760),
         child: Container(
-          padding: const EdgeInsets.all(14),
+          padding: const EdgeInsets.all(12),
           decoration: BoxDecoration(
             color: Colors.white,
-            borderRadius: BorderRadius.circular(14),
+            borderRadius: BorderRadius.circular(AppRadius.card),
             border: Border.all(color: borderColor),
-            boxShadow: [
-              BoxShadow(
-                color: palette.shadow.withValues(alpha: 0.05),
-                blurRadius: 10,
-                offset: const Offset(0, 5),
-              ),
-            ],
           ),
           child: Column(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
               Text(label, style: theme.textTheme.labelLarge),
-              const SizedBox(height: 6),
+              const SizedBox(height: 4),
               SelectableText(
                 text.isEmpty ? appText('暂无内容。', 'No content yet.') : text,
                 style: theme.textTheme.bodyLarge?.copyWith(
                   color: theme.colorScheme.onSurface,
-                  height: 1.55,
+                  height: 1.45,
                 ),
               ),
             ],
@@ -1450,19 +1444,12 @@ class _TaskStatusCard extends StatelessWidget {
         constraints: const BoxConstraints(maxWidth: 760),
         child: Material(
           color: Colors.white,
-          borderRadius: BorderRadius.circular(14),
+          borderRadius: BorderRadius.circular(AppRadius.card),
           child: Container(
-            padding: const EdgeInsets.all(12),
+            padding: const EdgeInsets.all(AppSpacing.sm),
             decoration: BoxDecoration(
-              borderRadius: BorderRadius.circular(14),
+              borderRadius: BorderRadius.circular(AppRadius.card),
               border: Border.all(color: palette.strokeSoft),
-              boxShadow: [
-                BoxShadow(
-                  color: palette.shadow.withValues(alpha: 0.03),
-                  blurRadius: 10,
-                  offset: const Offset(0, 6),
-                ),
-              ],
             ),
             child: Column(
               crossAxisAlignment: CrossAxisAlignment.start,
@@ -1471,15 +1458,15 @@ class _TaskStatusCard extends StatelessWidget {
                   crossAxisAlignment: CrossAxisAlignment.start,
                   children: [
                     Container(
-                      width: 28,
-                      height: 28,
+                      width: 24,
+                      height: 24,
                       decoration: BoxDecoration(
                         color: statusStyle.backgroundColor,
-                        borderRadius: BorderRadius.circular(9),
+                        borderRadius: BorderRadius.circular(8),
                       ),
                       child: Icon(
                         icon,
-                        size: 15,
+                        size: 14,
                         color: statusStyle.foregroundColor,
                       ),
                     ),
@@ -1502,16 +1489,16 @@ class _TaskStatusCard extends StatelessWidget {
                     ),
                   ],
                 ),
-                const SizedBox(height: 8),
+                const SizedBox(height: 6),
                 Container(
                   width: double.infinity,
                   padding: const EdgeInsets.symmetric(
-                    horizontal: 10,
-                    vertical: 8,
+                    horizontal: 8,
+                    vertical: 6,
                   ),
                   decoration: BoxDecoration(
                     color: palette.surfaceSecondary,
-                    borderRadius: BorderRadius.circular(14),
+                    borderRadius: BorderRadius.circular(10),
                   ),
                   child: Wrap(
                     spacing: 10,
@@ -1528,7 +1515,7 @@ class _TaskStatusCard extends StatelessWidget {
                     ],
                   ),
                 ),
-                const SizedBox(height: 8),
+                const SizedBox(height: 6),
                 Row(
                   children: [
                     Text(
@@ -1608,18 +1595,18 @@ class _ToolCallTileState extends State<_ToolCallTile> {
         child: Container(
           decoration: BoxDecoration(
             color: Colors.white,
-            borderRadius: BorderRadius.circular(12),
+            borderRadius: BorderRadius.circular(AppRadius.card),
             border: Border.all(color: palette.strokeSoft),
           ),
           child: Column(
             children: [
               InkWell(
-                borderRadius: BorderRadius.circular(12),
+                borderRadius: BorderRadius.circular(AppRadius.card),
                 onTap: () => setState(() => _expanded = !_expanded),
                 child: Padding(
                   padding: const EdgeInsets.symmetric(
-                    horizontal: 12,
-                    vertical: 10,
+                    horizontal: 10,
+                    vertical: 8,
                   ),
                   child: Row(
                     children: [
@@ -1653,7 +1640,7 @@ class _ToolCallTileState extends State<_ToolCallTile> {
                           ),
                         ),
                       ),
-                      const SizedBox(width: 10),
+                      const SizedBox(width: 8),
                       _StatusPill(
                         label: _toolCallStatusLabel(statusLabel),
                         backgroundColor: statusStyle.backgroundColor,
@@ -1677,12 +1664,12 @@ class _ToolCallTileState extends State<_ToolCallTile> {
                   curve: Curves.easeOutCubic,
                   child: _expanded
                       ? Padding(
-                          padding: const EdgeInsets.fromLTRB(12, 0, 12, 10),
+                          padding: const EdgeInsets.fromLTRB(AppSpacing.sm, 0, AppSpacing.sm, AppSpacing.xs),
                           child: Column(
                             crossAxisAlignment: CrossAxisAlignment.start,
                             children: [
                               Divider(height: 1, color: palette.strokeSoft),
-                              const SizedBox(height: 8),
+                              const SizedBox(height: 6),
                               Text(
                                 widget.summary.trim().isEmpty
                                     ? appText(
@@ -1692,7 +1679,7 @@ class _ToolCallTileState extends State<_ToolCallTile> {
                                     : widget.summary.trim(),
                                 style: theme.textTheme.bodySmall,
                               ),
-                              const SizedBox(height: 6),
+                              const SizedBox(height: 4),
                               TextButton(
                                 onPressed: widget.onOpenDetail,
                                 child: Text(appText('打开详情', 'Open detail')),
@@ -1725,12 +1712,12 @@ class _StatusPill extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return Container(
-      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 5),
+      padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
       decoration: BoxDecoration(
         color:
             backgroundColor ??
             Theme.of(context).colorScheme.surfaceContainerHighest,
-        borderRadius: BorderRadius.circular(999),
+        borderRadius: BorderRadius.circular(AppRadius.badge),
       ),
       child: Text(
         label,
@@ -1761,14 +1748,14 @@ class _ConnectionChip extends StatelessWidget {
     };
 
     return Container(
-      padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
+      padding: const EdgeInsets.symmetric(horizontal: AppSpacing.xs, vertical: 5),
       decoration: BoxDecoration(
         color: color,
-        borderRadius: BorderRadius.circular(999),
+        borderRadius: BorderRadius.circular(AppRadius.chip),
       ),
       child: Text(
         '${connection.status.label} · ${connection.remoteAddress ?? appText('未连接目标', 'No target')}',
-        style: theme.textTheme.labelLarge,
+        style: theme.textTheme.labelMedium,
       ),
     );
   }
diff --git a/lib/features/modules/modules_page.dart b/lib/features/modules/modules_page.dart
index 2536465c..d11a76da 100644
--- a/lib/features/modules/modules_page.dart
+++ b/lib/features/modules/modules_page.dart
@@ -62,7 +62,7 @@ class _ModulesPageState extends State<ModulesPage> {
       animation: controller,
       builder: (context, _) {
         return SingleChildScrollView(
-          padding: const EdgeInsets.fromLTRB(32, 32, 32, 16),
+          padding: const EdgeInsets.fromLTRB(32, 32, 32, 8),
           child: Column(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
diff --git a/lib/features/secrets/secrets_page.dart b/lib/features/secrets/secrets_page.dart
index 89ccc817..ae16c6f2 100644
--- a/lib/features/secrets/secrets_page.dart
+++ b/lib/features/secrets/secrets_page.dart
@@ -35,7 +35,7 @@ class _SecretsPageState extends State<SecretsPage> {
       animation: controller,
       builder: (context, _) {
         return SingleChildScrollView(
-          padding: const EdgeInsets.fromLTRB(32, 32, 32, 16),
+          padding: const EdgeInsets.fromLTRB(32, 32, 32, 8),
           child: Column(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
diff --git a/lib/features/settings/settings_page.dart b/lib/features/settings/settings_page.dart
index 5f58b3cd..7539b230 100644
--- a/lib/features/settings/settings_page.dart
+++ b/lib/features/settings/settings_page.dart
@@ -70,7 +70,7 @@ class _SettingsPageState extends State<SettingsPage> {
       builder: (context, _) {
         final settings = controller.settings;
         return SingleChildScrollView(
-          padding: const EdgeInsets.fromLTRB(32, 32, 32, 16),
+          padding: const EdgeInsets.fromLTRB(32, 32, 32, 8),
           child: Column(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
diff --git a/lib/features/tasks/tasks_page.dart b/lib/features/tasks/tasks_page.dart
index e8445941..ca260020 100644
--- a/lib/features/tasks/tasks_page.dart
+++ b/lib/features/tasks/tasks_page.dart
@@ -67,7 +67,7 @@ class _TasksPageState extends State<TasksPage> {
       animation: controller,
       builder: (context, _) {
         return SingleChildScrollView(
-          padding: const EdgeInsets.fromLTRB(32, 32, 32, 16),
+          padding: const EdgeInsets.fromLTRB(32, 32, 32, 8),
           child: Column(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
diff --git a/lib/theme/app_theme.dart b/lib/theme/app_theme.dart
index c02ff532..0666fe9e 100644
--- a/lib/theme/app_theme.dart
+++ b/lib/theme/app_theme.dart
@@ -3,6 +3,79 @@ import 'package:flutter/material.dart';
 
 import 'app_palette.dart';
 
+/// Design tokens for the XWorkmate design system.
+/// Follows a modern AI developer tool design language with:
+/// - 8px grid spacing
+/// - Compact, neutral, professional aesthetic
+/// - Consistent border radii
+class AppSpacing {
+  AppSpacing._();
+
+  // 8px grid system
+  static const double xxs = 4.0;
+  static const double xs = 8.0;
+  static const double sm = 12.0;
+  static const double md = 16.0;
+  static const double lg = 24.0;
+  static const double xl = 32.0;
+}
+
+class AppRadius {
+  AppRadius._();
+
+  static const double card = 12.0;
+  static const double button = 8.0;
+  static const double input = 10.0;
+  static const double chip = 12.0;
+  static const double badge = 10.0;
+  static const double dialog = 16.0;
+  static const double sidebar = 14.0;
+  static const double icon = 8.0;
+}
+
+class AppTypography {
+  AppTypography._();
+
+  // H1 - 22px weight 600
+  static const double h1Size = 22.0;
+  static const FontWeight h1Weight = FontWeight.w600;
+  static const double h1Height = 1.25;
+
+  // H2 - 18px weight 600
+  static const double h2Size = 18.0;
+  static const FontWeight h2Weight = FontWeight.w600;
+  static const double h2Height = 1.3;
+
+  // Body - 14px weight 400
+  static const double bodySize = 14.0;
+  static const FontWeight bodyWeight = FontWeight.w400;
+  static const double bodyHeight = 1.4;
+
+  // Meta - 12px weight 400
+  static const double metaSize = 12.0;
+  static const FontWeight metaWeight = FontWeight.w400;
+  static const double metaHeight = 1.45;
+}
+
+class AppSizes {
+  AppSizes._();
+
+  // Sidebar
+  static const double sidebarItemHeight = 36.0;
+  static const double sidebarIconSize = 18.0;
+  static const double sidebarTextSize = 14.0;
+  static const double sidebarExpandedWidth = 204.0;
+  static const double sidebarCollapsedWidth = 72.0;
+
+  // Input area
+  static const double textareaHeight = 48.0;
+  static const double toolbarHeight = 36.0;
+
+  // Buttons
+  static const double buttonHeightDesktop = 34.0;
+  static const double buttonHeightMobile = 36.0;
+}
+
 class AppTheme {
   static ThemeData light() =>
       _theme(brightness: Brightness.light, palette: AppPalette.light);
@@ -83,7 +156,7 @@ class AppTheme {
         shadowColor: palette.shadow,
         surfaceTintColor: Colors.transparent,
         shape: RoundedRectangleBorder(
-          borderRadius: BorderRadius.circular(16),
+          borderRadius: BorderRadius.circular(AppRadius.card),
           side: BorderSide(color: palette.strokeSoft),
         ),
       ),
@@ -91,7 +164,7 @@ class AppTheme {
         backgroundColor: palette.surfaceSecondary,
         side: BorderSide(color: palette.strokeSoft),
         labelStyle: tunedTextTheme.labelMedium,
-        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(10)),
+        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(AppRadius.chip)),
         padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 4),
       ),
       filledButtonTheme: FilledButtonThemeData(
@@ -99,13 +172,13 @@ class AppTheme {
           textStyle: tunedTextTheme.labelLarge?.copyWith(
             fontWeight: FontWeight.w500,
           ),
-          minimumSize: Size(0, isDesktop ? 34 : 36),
+          minimumSize: Size(0, isDesktop ? AppSizes.buttonHeightDesktop : AppSizes.buttonHeightMobile),
           padding: EdgeInsets.symmetric(
-            horizontal: isDesktop ? 12 : 14,
-            vertical: isDesktop ? 8 : 9,
+            horizontal: AppSpacing.sm,
+            vertical: AppSpacing.xs,
           ),
           shape: RoundedRectangleBorder(
-            borderRadius: BorderRadius.circular(10),
+            borderRadius: BorderRadius.circular(AppRadius.button),
           ),
         ),
       ),
@@ -115,13 +188,13 @@ class AppTheme {
           textStyle: tunedTextTheme.labelLarge?.copyWith(
             fontWeight: FontWeight.w500,
           ),
-          minimumSize: Size(0, isDesktop ? 34 : 36),
+          minimumSize: Size(0, isDesktop ? AppSizes.buttonHeightDesktop : AppSizes.buttonHeightMobile),
           padding: EdgeInsets.symmetric(
-            horizontal: isDesktop ? 12 : 14,
-            vertical: isDesktop ? 8 : 9,
+            horizontal: AppSpacing.sm,
+            vertical: AppSpacing.xs,
           ),
           shape: RoundedRectangleBorder(
-            borderRadius: BorderRadius.circular(10),
+            borderRadius: BorderRadius.circular(AppRadius.button),
           ),
           side: BorderSide(color: palette.strokeSoft),
         ),
@@ -134,11 +207,11 @@ class AppTheme {
           ),
           minimumSize: Size(0, isDesktop ? 32 : 34),
           padding: EdgeInsets.symmetric(
-            horizontal: isDesktop ? 10 : 12,
-            vertical: isDesktop ? 8 : 9,
+            horizontal: AppSpacing.sm,
+            vertical: AppSpacing.xs,
           ),
           shape: RoundedRectangleBorder(
-            borderRadius: BorderRadius.circular(10),
+            borderRadius: BorderRadius.circular(AppRadius.button),
           ),
         ),
       ),
@@ -147,7 +220,7 @@ class AppTheme {
           foregroundColor: palette.textSecondary,
           backgroundColor: palette.surfaceSecondary,
           shape: RoundedRectangleBorder(
-            borderRadius: BorderRadius.circular(10),
+            borderRadius: BorderRadius.circular(AppRadius.icon),
             side: BorderSide(color: palette.strokeSoft),
           ),
           minimumSize: const Size(34, 34),
@@ -164,19 +237,19 @@ class AppTheme {
           color: palette.textMuted,
         ),
         contentPadding: EdgeInsets.symmetric(
-          horizontal: isDesktop ? 16 : 18,
-          vertical: isDesktop ? 12 : 13,
+          horizontal: AppSpacing.md,
+          vertical: AppSpacing.sm,
         ),
         border: OutlineInputBorder(
-          borderRadius: BorderRadius.circular(10),
+          borderRadius: BorderRadius.circular(AppRadius.input),
           borderSide: BorderSide(color: palette.strokeSoft),
         ),
         enabledBorder: OutlineInputBorder(
-          borderRadius: BorderRadius.circular(10),
+          borderRadius: BorderRadius.circular(AppRadius.input),
           borderSide: BorderSide(color: palette.strokeSoft),
         ),
         focusedBorder: OutlineInputBorder(
-          borderRadius: BorderRadius.circular(10),
+          borderRadius: BorderRadius.circular(AppRadius.input),
           borderSide: BorderSide(color: palette.accent.withValues(alpha: 0.42)),
         ),
       ),
@@ -196,10 +269,10 @@ class AppTheme {
             return palette.textSecondary;
           }),
           padding: const WidgetStatePropertyAll(
-            EdgeInsets.symmetric(horizontal: 12, vertical: 8),
+            EdgeInsets.symmetric(horizontal: AppSpacing.sm, vertical: AppSpacing.xs),
           ),
           shape: WidgetStatePropertyAll(
-            RoundedRectangleBorder(borderRadius: BorderRadius.circular(10)),
+            RoundedRectangleBorder(borderRadius: BorderRadius.circular(AppRadius.chip)),
           ),
           textStyle: WidgetStatePropertyAll(
             tunedTextTheme.labelLarge?.copyWith(fontWeight: FontWeight.w500),
@@ -210,7 +283,7 @@ class AppTheme {
         behavior: SnackBarBehavior.floating,
         backgroundColor: palette.surfaceTertiary,
         contentTextStyle: TextStyle(color: palette.textPrimary),
-        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(16)),
+        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(AppRadius.dialog)),
       ),
     );
   }
@@ -238,28 +311,30 @@ class AppTheme {
     }
 
     return base.copyWith(
+      // H1: 22px weight 600
       displaySmall: withUiFont(
         base.displaySmall?.copyWith(
-          fontSize: isDesktop ? 22 : 24,
-          fontWeight: FontWeight.w600,
+          fontSize: AppTypography.h1Size,
+          fontWeight: AppTypography.h1Weight,
           letterSpacing: -0.24,
-          height: 1.25,
+          height: AppTypography.h1Height,
         ),
       ),
       headlineSmall: withUiFont(
         base.headlineSmall?.copyWith(
-          fontSize: isDesktop ? 22 : 24,
-          fontWeight: FontWeight.w600,
+          fontSize: AppTypography.h1Size,
+          fontWeight: AppTypography.h1Weight,
           letterSpacing: -0.24,
-          height: 1.25,
+          height: AppTypography.h1Height,
         ),
       ),
+      // H2: 18px weight 600
       titleLarge: withUiFont(
         base.titleLarge?.copyWith(
-          fontSize: isDesktop ? 18 : 19,
-          fontWeight: FontWeight.w600,
+          fontSize: AppTypography.h2Size,
+          fontWeight: AppTypography.h2Weight,
           letterSpacing: -0.16,
-          height: 1.3,
+          height: AppTypography.h2Height,
         ),
       ),
       titleMedium: withUiFont(
@@ -277,27 +352,29 @@ class AppTheme {
           height: 1.4,
         ),
       ),
+      // Body: 14px weight 400
       bodyLarge: withUiFont(
         base.bodyLarge?.copyWith(
-          fontSize: isDesktop ? 14 : 15,
-          fontWeight: FontWeight.w400,
-          height: 1.4,
+          fontSize: AppTypography.bodySize,
+          fontWeight: AppTypography.bodyWeight,
+          height: AppTypography.bodyHeight,
           color: palette.textPrimary,
         ),
       ),
       bodyMedium: withUiFont(
         base.bodyMedium?.copyWith(
-          fontSize: 14,
-          fontWeight: FontWeight.w400,
-          height: 1.4,
+          fontSize: AppTypography.bodySize,
+          fontWeight: AppTypography.bodyWeight,
+          height: AppTypography.bodyHeight,
           color: palette.textSecondary,
         ),
       ),
+      // Meta: 12px weight 400
       bodySmall: withUiFont(
         base.bodySmall?.copyWith(
-          fontSize: isDesktop ? 12 : 13,
-          fontWeight: FontWeight.w400,
-          height: 1.45,
+          fontSize: AppTypography.metaSize,
+          fontWeight: AppTypography.metaWeight,
+          height: AppTypography.metaHeight,
           color: palette.textMuted,
         ),
       ),
diff --git a/lib/widgets/detail_drawer.dart b/lib/widgets/detail_drawer.dart
index f5e7ee91..a1d9e0d1 100644
--- a/lib/widgets/detail_drawer.dart
+++ b/lib/widgets/detail_drawer.dart
@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 
 import '../models/app_models.dart';
 import '../theme/app_palette.dart';
+import '../theme/app_theme.dart';
 import 'status_badge.dart';
 
 class DetailDrawer extends StatelessWidget {
@@ -16,10 +17,10 @@ class DetailDrawer extends StatelessWidget {
 
     return Container(
       width: 360,
-      margin: const EdgeInsets.fromLTRB(0, 24, 24, 24),
+      margin: const EdgeInsets.fromLTRB(0, AppSpacing.lg, AppSpacing.lg, AppSpacing.lg),
       decoration: BoxDecoration(
         color: palette.surfacePrimary,
-        borderRadius: BorderRadius.circular(28),
+        borderRadius: BorderRadius.circular(AppRadius.dialog),
         border: Border.all(color: palette.strokeSoft),
         boxShadow: [
           BoxShadow(
@@ -46,23 +47,14 @@ class DetailSheet extends StatelessWidget {
     final mediaQuery = MediaQuery.of(context);
 
     return Container(
-      margin: EdgeInsets.fromLTRB(12, mediaQuery.padding.top + 12, 12, 12),
+      margin: EdgeInsets.fromLTRB(AppSpacing.sm, mediaQuery.padding.top + AppSpacing.sm, AppSpacing.sm, AppSpacing.sm),
       decoration: BoxDecoration(
         color: palette.surfacePrimary,
-        borderRadius: BorderRadius.circular(28),
+        borderRadius: BorderRadius.circular(AppRadius.dialog),
         border: Border.all(color: palette.strokeSoft),
-        boxShadow: [
-          BoxShadow(
-            color: palette.shadow.withValues(alpha: 0.16),
-            blurRadius: 28,
-            offset: const Offset(0, 18),
-          ),
-        ],
-      ),
-      child: SafeArea(
-        top: false,
-        child: _DetailPanelContent(data: data, onClose: onClose),
       ),
+      constraints: const BoxConstraints(maxWidth: 480),
+      child: _DetailPanelContent(data: data, onClose: onClose),
     );
   }
 }
@@ -75,11 +67,14 @@ class _DetailPanelContent extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final palette = context.palette;
+
     return Column(
-      crossAxisAlignment: CrossAxisAlignment.start,
+      crossAxisAlignment: CrossAxisAlignment.stretch,
       children: [
         Padding(
-          padding: const EdgeInsets.fromLTRB(22, 22, 16, 16),
+          padding: const EdgeInsets.all(AppSpacing.md),
           child: Row(
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
@@ -87,81 +82,92 @@ class _DetailPanelContent extends StatelessWidget {
                 width: 44,
                 height: 44,
                 decoration: BoxDecoration(
-                  color: context.palette.accentMuted,
-                  borderRadius: BorderRadius.circular(14),
+                  color: palette.accentMuted,
+                  borderRadius: BorderRadius.circular(AppRadius.button),
                 ),
-                child: Icon(data.icon, color: context.palette.accent),
+                child: Icon(data.icon, color: palette.accent, size: 22),
               ),
-              const SizedBox(width: 14),
+              const SizedBox(width: AppSpacing.sm),
               Expanded(
                 child: Column(
                   crossAxisAlignment: CrossAxisAlignment.start,
                   children: [
-                    Text(
-                      data.subtitle,
-                      style: Theme.of(context).textTheme.bodySmall,
-                    ),
-                    const SizedBox(height: 4),
-                    Text(
-                      data.title,
-                      style: Theme.of(context).textTheme.titleLarge,
-                    ),
-                    const SizedBox(height: 10),
-                    StatusBadge(status: data.status, compact: true),
+                    Text(data.title, style: theme.textTheme.headlineSmall),
+                    const SizedBox(height: AppSpacing.xxs),
+                    if (data.status != null)
+                      StatusBadge(status: data.status!, compact: true),
                   ],
                 ),
               ),
+              const SizedBox(width: AppSpacing.xs),
               IconButton(
                 onPressed: onClose,
                 icon: const Icon(Icons.close_rounded),
+                iconSize: 20,
+                style: IconButton.styleFrom(
+                  foregroundColor: palette.textSecondary,
+                  backgroundColor: palette.surfaceSecondary,
+                ),
               ),
             ],
           ),
         ),
-        Padding(
-          padding: const EdgeInsets.symmetric(horizontal: 22),
-          child: Text(
-            data.description,
-            style: Theme.of(context).textTheme.bodyMedium,
+        Divider(height: 1, color: palette.strokeSoft),
+        if (data.subtitle != null && data.subtitle!.isNotEmpty)
+          Padding(
+            padding: const EdgeInsets.all(AppSpacing.md),
+            child: Text(
+              data.subtitle!,
+              style: theme.textTheme.bodySmall,
+            ),
           ),
-        ),
-        const SizedBox(height: 16),
-        Padding(
-          padding: const EdgeInsets.symmetric(horizontal: 22),
-          child: Wrap(
-            spacing: 8,
-            runSpacing: 8,
-            children: data.meta
-                .map(
-                  (item) => Chip(
-                    label: Text(item),
-                    visualDensity: VisualDensity.compact,
-                  ),
-                )
-                .toList(),
-          ),
-        ),
-        const SizedBox(height: 18),
         Expanded(
           child: ListView(
-            padding: const EdgeInsets.fromLTRB(22, 0, 22, 22),
+            padding: const EdgeInsets.fromLTRB(AppSpacing.md, 0, AppSpacing.md, AppSpacing.md),
             children: [
-              ...data.sections.map(
-                (section) => Padding(
-                  padding: const EdgeInsets.only(bottom: 18),
-                  child: _DetailSectionCard(section: section),
+              if (data.description.isNotEmpty)
+                Text(data.description, style: theme.textTheme.bodyMedium),
+              if (data.meta.isNotEmpty) ...[
+                const SizedBox(height: AppSpacing.sm),
+                Wrap(
+                  spacing: AppSpacing.xs,
+                  runSpacing: AppSpacing.xxs,
+                  children: data.meta.map((item) {
+                    return Container(
+                      padding: const EdgeInsets.symmetric(horizontal: AppSpacing.xs, vertical: AppSpacing.xxs),
+                      decoration: BoxDecoration(
+                        color: palette.surfaceSecondary,
+                        borderRadius: BorderRadius.circular(AppRadius.badge),
+                      ),
+                      child: Text(
+                        item,
+                        style: theme.textTheme.labelSmall?.copyWith(
+                          color: palette.textSecondary,
+                        ),
+                      ),
+                    );
+                  }).toList(),
                 ),
-              ),
-              Wrap(
-                spacing: 8,
-                runSpacing: 8,
-                children: data.actions
-                    .map(
-                      (action) =>
-                          OutlinedButton(onPressed: () {}, child: Text(action)),
-                    )
-                    .toList(),
-              ),
+              ],
+              if (data.actions.isNotEmpty) ...[
+                const SizedBox(height: AppSpacing.sm),
+                Wrap(
+                  spacing: AppSpacing.xs,
+                  runSpacing: AppSpacing.xs,
+                  children: data.actions.map((action) {
+                    return TextButton(
+                      onPressed: () {},
+                      child: Text(action),
+                    );
+                  }).toList(),
+                ),
+              ],
+              ...data.sections.map((section) {
+                return Padding(
+                  padding: const EdgeInsets.only(top: AppSpacing.md),
+                  child: _DetailSection(section: section),
+                );
+              }),
             ],
           ),
         ),
@@ -170,52 +176,52 @@ class _DetailPanelContent extends StatelessWidget {
   }
 }
 
-class _DetailSectionCard extends StatelessWidget {
-  const _DetailSectionCard({required this.section});
+class _DetailSection extends StatelessWidget {
+  const _DetailSection({required this.section});
 
   final DetailSection section;
 
   @override
   Widget build(BuildContext context) {
+    final theme = Theme.of(context);
     final palette = context.palette;
 
-    return Container(
-      padding: const EdgeInsets.all(16),
-      decoration: BoxDecoration(
-        color: palette.surfaceSecondary,
-        borderRadius: BorderRadius.circular(18),
-        border: Border.all(color: palette.strokeSoft),
-      ),
-      child: Column(
-        crossAxisAlignment: CrossAxisAlignment.start,
-        children: [
-          Text(section.title, style: Theme.of(context).textTheme.titleMedium),
-          const SizedBox(height: 12),
-          ...section.items.map(
-            (item) => Padding(
-              padding: const EdgeInsets.only(bottom: 10),
-              child: Row(
-                children: [
-                  Expanded(
-                    child: Text(
-                      item.label,
-                      style: Theme.of(context).textTheme.bodySmall,
-                    ),
-                  ),
-                  const SizedBox(width: 16),
-                  Flexible(
-                    child: Text(
-                      item.value,
-                      textAlign: TextAlign.right,
-                      style: Theme.of(context).textTheme.labelLarge,
-                    ),
-                  ),
-                ],
-              ),
-            ),
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        Text(
+          section.title,
+          style: theme.textTheme.labelLarge?.copyWith(
+            color: palette.textSecondary,
           ),
-        ],
-      ),
+        ),
+        const SizedBox(height: AppSpacing.xs),
+        ...section.items.map((item) {
+          return Padding(
+            padding: const EdgeInsets.only(bottom: AppSpacing.xs),
+            child: Row(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                SizedBox(
+                  width: 80,
+                  child: Text(
+                    item.label,
+                    style: theme.textTheme.bodySmall?.copyWith(
+                      color: palette.textMuted,
+                    ),
+                  ),
+                ),
+                Expanded(
+                  child: Text(
+                    item.value,
+                    style: theme.textTheme.bodyMedium,
+                  ),
+                ),
+              ],
+            ),
+          );
+        }),
+      ],
     );
   }
 }
diff --git a/lib/widgets/gateway_connect_dialog.dart b/lib/widgets/gateway_connect_dialog.dart
index 07378063..43979086 100644
--- a/lib/widgets/gateway_connect_dialog.dart
+++ b/lib/widgets/gateway_connect_dialog.dart
@@ -5,6 +5,7 @@ import '../i18n/app_language.dart';
 import '../runtime/runtime_bootstrap.dart';
 import '../runtime/runtime_models.dart';
 import 'section_tabs.dart';
+import '../theme/app_theme.dart';
 
 class GatewayConnectDialog extends StatefulWidget {
   const GatewayConnectDialog({
diff --git a/lib/widgets/metric_card.dart b/lib/widgets/metric_card.dart
index 57c67771..ed2058cd 100644
--- a/lib/widgets/metric_card.dart
+++ b/lib/widgets/metric_card.dart
@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 
 import '../models/app_models.dart';
 import '../theme/app_palette.dart';
+import '../theme/app_theme.dart';
 import 'status_badge.dart';
 import 'surface_card.dart';
 
@@ -25,7 +26,7 @@ class MetricCard extends StatelessWidget {
                 height: 40,
                 decoration: BoxDecoration(
                   color: palette.accentMuted,
-                  borderRadius: BorderRadius.circular(14),
+                  borderRadius: BorderRadius.circular(AppRadius.card),
                 ),
                 child: Icon(metric.icon, color: palette.accent, size: 20),
               ),
@@ -34,11 +35,11 @@ class MetricCard extends StatelessWidget {
                 StatusBadge(status: metric.status!, compact: true),
             ],
           ),
-          const SizedBox(height: 18),
+          const SizedBox(height: AppSpacing.lg),
           Text(metric.label, style: Theme.of(context).textTheme.bodyMedium),
-          const SizedBox(height: 6),
+          const SizedBox(height: AppSpacing.xxs),
           Text(metric.value, style: Theme.of(context).textTheme.headlineSmall),
-          const SizedBox(height: 6),
+          const SizedBox(height: AppSpacing.xxs),
           Text(metric.caption, style: Theme.of(context).textTheme.bodySmall),
         ],
       ),
diff --git a/lib/widgets/section_header.dart b/lib/widgets/section_header.dart
index 2604a961..2aedc034 100644
--- a/lib/widgets/section_header.dart
+++ b/lib/widgets/section_header.dart
@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import '../theme/app_theme.dart';
 
 class SectionHeader extends StatelessWidget {
   const SectionHeader({
@@ -22,7 +23,7 @@ class SectionHeader extends StatelessWidget {
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
               Text(title, style: Theme.of(context).textTheme.titleLarge),
-              const SizedBox(height: 8),
+              const SizedBox(height: AppSpacing.xs),
               Text(subtitle, style: Theme.of(context).textTheme.bodySmall),
             ],
           ),
diff --git a/lib/widgets/section_tabs.dart b/lib/widgets/section_tabs.dart
index ce598bc7..7aa47d79 100644
--- a/lib/widgets/section_tabs.dart
+++ b/lib/widgets/section_tabs.dart
@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 
 import '../theme/app_palette.dart';
+import '../theme/app_theme.dart';
 
 enum SectionTabsSize { small, medium }
 
@@ -23,20 +24,20 @@ class SectionTabs extends StatelessWidget {
     final palette = context.palette;
     final padding = switch (size) {
       SectionTabsSize.small => const EdgeInsets.symmetric(
-        horizontal: 12,
+        horizontal: AppSpacing.sm,
         vertical: 6,
       ),
       SectionTabsSize.medium => const EdgeInsets.symmetric(
-        horizontal: 12,
-        vertical: 8,
+        horizontal: AppSpacing.sm,
+        vertical: AppSpacing.xs,
       ),
     };
 
     return Container(
-      padding: const EdgeInsets.all(4),
+      padding: const EdgeInsets.all(AppSpacing.xxs),
       decoration: BoxDecoration(
         color: palette.surfaceSecondary,
-        borderRadius: BorderRadius.circular(12),
+        borderRadius: BorderRadius.circular(AppRadius.chip),
         border: Border.all(color: palette.strokeSoft),
       ),
       child: SingleChildScrollView(
@@ -45,7 +46,7 @@ class SectionTabs extends StatelessWidget {
           children: items.map((item) {
             final selected = item == value;
             return Padding(
-              padding: const EdgeInsets.only(right: 4),
+              padding: const EdgeInsets.only(right: AppSpacing.xxs),
               child: _SectionTabChip(
                 label: item,
                 selected: selected,
@@ -96,12 +97,12 @@ class _SectionTabChipState extends State<_SectionTabChip> {
               : _hovered
               ? palette.hover
               : Colors.transparent,
-          borderRadius: BorderRadius.circular(10),
+          borderRadius: BorderRadius.circular(AppRadius.button),
         ),
         child: Material(
           color: Colors.transparent,
           child: InkWell(
-            borderRadius: BorderRadius.circular(10),
+            borderRadius: BorderRadius.circular(AppRadius.button),
             onTap: widget.onTap,
             child: Padding(
               padding: widget.padding,
diff --git a/lib/widgets/sidebar_navigation.dart b/lib/widgets/sidebar_navigation.dart
index f9a9af07..2242e00b 100644
--- a/lib/widgets/sidebar_navigation.dart
+++ b/lib/widgets/sidebar_navigation.dart
@@ -3,6 +3,7 @@ import 'package:flutter/material.dart';
 import '../i18n/app_language.dart';
 import '../models/app_models.dart';
 import '../theme/app_palette.dart';
+import '../theme/app_theme.dart';
 
 class SidebarNavigation extends StatelessWidget {
   const SidebarNavigation({
@@ -51,23 +52,23 @@ class SidebarNavigation extends StatelessWidget {
     final isCollapsed = sidebarState == AppSidebarState.collapsed;
     final expandedWidth =
         expandedWidthOverride ??
-        (appLanguage == AppLanguage.zh ? 204.0 : 220.0);
+        (appLanguage == AppLanguage.zh ? AppSizes.sidebarExpandedWidth : 220.0);
 
     return AnimatedContainer(
       duration: const Duration(milliseconds: 220),
       curve: Curves.easeOutCubic,
-      width: isExpanded ? expandedWidth : 72,
+      width: isExpanded ? expandedWidth : AppSizes.sidebarCollapsedWidth,
       height: double.infinity,
-      margin: const EdgeInsets.fromLTRB(8, 8, 6, 8),
+      margin: const EdgeInsets.fromLTRB(AppSpacing.xs, AppSpacing.xs, 6, 0),
       decoration: BoxDecoration(
         color: palette.sidebar,
-        borderRadius: BorderRadius.circular(14),
+        borderRadius: BorderRadius.circular(AppRadius.sidebar),
         border: Border.all(
           color: palette.sidebarBorder.withValues(alpha: 0.72),
         ),
       ),
       child: Padding(
-        padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 8),
+        padding: const EdgeInsets.symmetric(horizontal: AppSpacing.xs, vertical: AppSpacing.xs),
         child: Column(
           crossAxisAlignment: CrossAxisAlignment.stretch,
           children: [
@@ -75,16 +76,16 @@ class SidebarNavigation extends StatelessWidget {
               isCollapsed: !isExpanded,
               onTap: isCollapsed ? onExpandFromCollapsed : null,
             ),
-            const SizedBox(height: 8),
+            const SizedBox(height: AppSpacing.xs),
             Container(height: 1, color: palette.sidebarBorder),
-            const SizedBox(height: 8),
+            const SizedBox(height: AppSpacing.xs),
             Expanded(
               child: ListView(
                 padding: EdgeInsets.zero,
                 children: [
                   ..._mainSections.map(
                     (section) => Padding(
-                      padding: const EdgeInsets.only(bottom: 4),
+                      padding: const EdgeInsets.only(bottom: AppSpacing.xxs),
                       child: SidebarNavItem(
                         section: section,
                         selected: currentSection == section,
@@ -93,9 +94,9 @@ class SidebarNavigation extends StatelessWidget {
                       ),
                     ),
                   ),
-                  const SizedBox(height: 8),
+                  const SizedBox(height: AppSpacing.xs),
                   Container(height: 1, color: palette.sidebarBorder),
-                  const SizedBox(height: 8),
+                  const SizedBox(height: AppSpacing.xs),
                   SidebarFooter(
                     isCollapsed: isCollapsed,
                     appLanguage: appLanguage,
@@ -133,13 +134,13 @@ class SidebarHeader extends StatelessWidget {
     final palette = context.palette;
 
     final content = Container(
-      width: isCollapsed ? 36 : 32,
-      height: isCollapsed ? 36 : 32,
+      width: isCollapsed ? AppSizes.sidebarItemHeight : 32,
+      height: isCollapsed ? AppSizes.sidebarItemHeight : 32,
       decoration: BoxDecoration(
-        borderRadius: BorderRadius.circular(10),
+        borderRadius: BorderRadius.circular(AppRadius.button),
         color: palette.accentMuted,
       ),
-      child: Icon(Icons.auto_awesome_rounded, color: palette.accent, size: 18),
+      child: Icon(Icons.auto_awesome_rounded, color: palette.accent, size: AppSizes.sidebarIconSize),
     );
 
     if (onTap == null) {
@@ -149,7 +150,7 @@ class SidebarHeader extends StatelessWidget {
     return Tooltip(
       message: appText('展开导航', 'Expand sidebar'),
       child: InkWell(
-        borderRadius: BorderRadius.circular(10),
+        borderRadius: BorderRadius.circular(AppRadius.button),
         onTap: onTap,
         child: Padding(
           padding: const EdgeInsets.symmetric(vertical: 2),
@@ -184,66 +185,89 @@ class _SidebarNavItemState extends State<SidebarNavItem> {
   @override
   Widget build(BuildContext context) {
     final palette = context.palette;
-    final active = widget.selected;
-    final background = active
+    final background = widget.selected
         ? palette.accentMuted
         : _hovered
         ? palette.hover
         : Colors.transparent;
-    final foreground = active ? palette.accent : palette.textSecondary;
 
-    final item = AnimatedContainer(
-      duration: const Duration(milliseconds: 160),
-      curve: Curves.easeOutCubic,
-      width: widget.collapsed ? null : double.infinity,
-      height: widget.collapsed ? 40 : 38,
-      decoration: BoxDecoration(
-        color: background,
-        borderRadius: BorderRadius.circular(10),
-      ),
-      child: Material(
-        color: Colors.transparent,
-        child: InkWell(
-          borderRadius: BorderRadius.circular(10),
-          onTap: widget.onTap,
-          child: Padding(
-            padding: EdgeInsets.symmetric(
-              horizontal: widget.collapsed ? 0 : 10,
-              vertical: 0,
-            ),
-            child: Row(
-              mainAxisAlignment: widget.collapsed
-                  ? MainAxisAlignment.center
-                  : MainAxisAlignment.start,
-              children: [
-                Icon(widget.section.icon, color: foreground, size: 18),
-                if (!widget.collapsed) ...[
-                  const SizedBox(width: 8),
-                  Expanded(
-                    child: Text(
-                      widget.section.label,
-                      maxLines: 1,
-                      overflow: TextOverflow.ellipsis,
-                      style: Theme.of(
-                        context,
-                      ).textTheme.labelLarge?.copyWith(color: foreground),
-                    ),
-                  ),
-                ],
-              ],
+    return Tooltip(
+      message: widget.collapsed ? _sectionLabel(widget.section) : '',
+      child: MouseRegion(
+        onEnter: (_) => setState(() => _hovered = true),
+        onExit: (_) => setState(() => _hovered = false),
+        child: AnimatedContainer(
+          duration: const Duration(milliseconds: 160),
+          decoration: BoxDecoration(
+            color: background,
+            borderRadius: BorderRadius.circular(AppRadius.button),
+          ),
+          child: Material(
+            color: Colors.transparent,
+            child: InkWell(
+              borderRadius: BorderRadius.circular(AppRadius.button),
+              onTap: widget.onTap,
+              child: Container(
+                height: AppSizes.sidebarItemHeight,
+                padding: const EdgeInsets.symmetric(horizontal: AppSpacing.xs),
+                child: widget.collapsed
+                    ? Center(
+                        child: Icon(
+                          _sectionIcon(widget.section),
+                          size: AppSizes.sidebarIconSize,
+                          color: widget.selected
+                              ? palette.accent
+                              : palette.textSecondary,
+                        ),
+                      )
+                    : Row(
+                        children: [
+                          Icon(
+                            _sectionIcon(widget.section),
+                            size: AppSizes.sidebarIconSize,
+                            color: widget.selected
+                                ? palette.accent
+                                : palette.textSecondary,
+                          ),
+                          const SizedBox(width: AppSpacing.xs),
+                          Text(
+                            _sectionLabel(widget.section),
+                            style: Theme.of(context).textTheme.labelLarge?.copyWith(
+                              color: widget.selected
+                                  ? palette.textPrimary
+                                  : palette.textSecondary,
+                            ),
+                          ),
+                        ],
+                      ),
+              ),
             ),
           ),
         ),
       ),
     );
+  }
 
-    return MouseRegion(
-      onEnter: (_) => setState(() => _hovered = true),
-      onExit: (_) => setState(() => _hovered = false),
-      child: widget.collapsed
-          ? Tooltip(message: widget.section.label, child: item)
-          : item,
-    );
+  IconData _sectionIcon(WorkspaceDestination section) {
+    return switch (section) {
+      WorkspaceDestination.assistant => Icons.auto_awesome_rounded,
+      WorkspaceDestination.tasks => Icons.task_alt_rounded,
+      WorkspaceDestination.modules => Icons.extension_rounded,
+      WorkspaceDestination.secrets => Icons.key_rounded,
+      WorkspaceDestination.settings => Icons.tune_rounded,
+      WorkspaceDestination.account => Icons.account_circle_rounded,
+    };
+  }
+
+  String _sectionLabel(WorkspaceDestination section) {
+    return switch (section) {
+      WorkspaceDestination.assistant => appText('助手', 'Assistant'),
+      WorkspaceDestination.tasks => appText('任务', 'Tasks'),
+      WorkspaceDestination.modules => appText('模块', 'Modules'),
+      WorkspaceDestination.secrets => appText('密钥', 'Secrets'),
+      WorkspaceDestination.settings => appText('设置', 'Settings'),
+      WorkspaceDestination.account => appText('账户', 'Account'),
+    };
   }
 }
 
@@ -251,12 +275,12 @@ class SidebarFooter extends StatelessWidget {
   const SidebarFooter({
     super.key,
     required this.isCollapsed,
-    required this.sidebarState,
     required this.appLanguage,
     required this.themeMode,
     required this.onToggleLanguage,
     required this.onOpenThemeToggle,
     required this.onOpenSettings,
+    required this.sidebarState,
     required this.onCycleSidebarState,
     required this.onOpenAccount,
     required this.accountName,
@@ -265,12 +289,12 @@ class SidebarFooter extends StatelessWidget {
   });
 
   final bool isCollapsed;
-  final AppSidebarState sidebarState;
   final AppLanguage appLanguage;
   final ThemeMode themeMode;
   final VoidCallback onToggleLanguage;
   final VoidCallback onOpenThemeToggle;
   final VoidCallback onOpenSettings;
+  final AppSidebarState sidebarState;
   final VoidCallback onCycleSidebarState;
   final VoidCallback onOpenAccount;
   final String accountName;
@@ -279,205 +303,161 @@ class SidebarFooter extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final theme = Theme.of(context);
     final palette = context.palette;
-    final themeLabel = themeMode == ThemeMode.dark
-        ? appText('切换浅色', 'Switch to light')
-        : appText('切换深色', 'Switch to dark');
-    final collapseLabel = switch (sidebarState) {
-      AppSidebarState.expanded => appText('折叠导航', 'Collapse sidebar'),
-      AppSidebarState.collapsed => appText('隐藏导航', 'Hide sidebar'),
-      AppSidebarState.hidden => appText('展开导航', 'Expand sidebar'),
-    };
 
-    final themeButton = Tooltip(
-      message: themeLabel,
-      child: IconButton(
-        iconSize: 18,
-        onPressed: onOpenThemeToggle,
-        icon: Icon(
-          themeMode == ThemeMode.dark
-              ? Icons.light_mode_rounded
-              : Icons.dark_mode_rounded,
-        ),
-      ),
-    );
-
-    final languageButton = Tooltip(
-      message: appText('切换语言', 'Switch language'),
-      child: _SidebarLanguageButton(
-        appLanguage: appLanguage,
-        compact: isCollapsed,
-        onPressed: onToggleLanguage,
-      ),
-    );
-
-    final settingsButton = Tooltip(
-      message: appText('打开设置', 'Open settings'),
-      child: IconButton(
-        iconSize: 18,
-        onPressed: onOpenSettings,
-        icon: const Icon(Icons.settings_rounded),
-      ),
-    );
-
-    final collapseButton = Tooltip(
-      message: collapseLabel,
-      child: IconButton(
-        iconSize: 18,
-        onPressed: onCycleSidebarState,
-        icon: Icon(switch (sidebarState) {
-          AppSidebarState.expanded => Icons.keyboard_double_arrow_left_rounded,
-          AppSidebarState.collapsed => Icons.visibility_off_outlined,
-          AppSidebarState.hidden => Icons.keyboard_double_arrow_right_rounded,
-        }),
-      ),
-    );
-
-    return Column(
-      mainAxisSize: MainAxisSize.min,
-      children: [
-        if (isCollapsed)
-          Column(
-            mainAxisSize: MainAxisSize.min,
-            children: [
-              themeButton,
-              const SizedBox(height: 4),
-              languageButton,
-              const SizedBox(height: 4),
-              settingsButton,
-              const SizedBox(height: 4),
-              collapseButton,
-            ],
-          )
-        else
-          Column(
-            crossAxisAlignment: CrossAxisAlignment.start,
-            children: [
-              _SidebarFooterActionTile(
-                icon: themeMode == ThemeMode.dark
-                    ? Icons.light_mode_rounded
-                    : Icons.dark_mode_rounded,
-                label: themeLabel,
-                onTap: onOpenThemeToggle,
-              ),
-              const SizedBox(height: 4),
-              _SidebarFooterActionTile(
-                icon: Icons.translate_rounded,
-                label: appText('语言', 'Language'),
-                trailingText: appLanguage == AppLanguage.zh ? '中文' : 'EN',
-                onTap: onToggleLanguage,
-              ),
-              const SizedBox(height: 4),
-              _SidebarFooterActionTile(
-                icon: Icons.settings_rounded,
-                label: appText('打开设置', 'Open settings'),
-                onTap: onOpenSettings,
-              ),
-              const SizedBox(height: 4),
-              _SidebarFooterActionTile(
-                icon: switch (sidebarState) {
-                  AppSidebarState.expanded =>
-                    Icons.keyboard_double_arrow_left_rounded,
-                  AppSidebarState.collapsed => Icons.visibility_off_outlined,
-                  AppSidebarState.hidden =>
-                    Icons.keyboard_double_arrow_right_rounded,
-                },
-                label: collapseLabel,
-                onTap: onCycleSidebarState,
-              ),
-            ],
+    if (isCollapsed) {
+      return Column(
+        crossAxisAlignment: CrossAxisAlignment.stretch,
+        children: [
+          Container(height: 1, color: palette.sidebarBorder),
+          const SizedBox(height: AppSpacing.xs),
+          _SidebarLanguageButton(
+            appLanguage: appLanguage,
+            compact: true,
+            onPressed: onToggleLanguage,
           ),
-        const SizedBox(height: 12),
-        if (isCollapsed)
-          Tooltip(
-            message: appText('账号', 'Account'),
-            child: InkWell(
-              borderRadius: BorderRadius.circular(10),
-              onTap: onOpenAccount,
-              child: Container(
-                width: double.infinity,
-                padding: const EdgeInsets.symmetric(vertical: 8),
-                decoration: BoxDecoration(
-                  color: accountSelected
-                      ? palette.accentMuted
-                      : palette.surfaceSecondary,
-                  borderRadius: BorderRadius.circular(10),
-                  border: Border.all(color: palette.strokeSoft),
-                ),
-                child: const Icon(Icons.account_circle_rounded, size: 20),
-              ),
-            ),
-          )
-        else
+          const SizedBox(height: AppSpacing.xs),
+          _SidebarActionButton(
+            icon: themeMode == ThemeMode.dark
+                ? Icons.dark_mode_rounded
+                : themeMode == ThemeMode.light
+                ? Icons.light_mode_rounded
+                : Icons.brightness_auto_rounded,
+            tooltip: appText('切换主题', 'Toggle theme'),
+            onPressed: onOpenThemeToggle,
+          ),
+          const SizedBox(height: AppSpacing.xs),
+          _SidebarActionButton(
+            icon: _sidebarStateIcon(sidebarState),
+            tooltip: _sidebarStateLabel(sidebarState),
+            onPressed: onCycleSidebarState,
+          ),
+          const SizedBox(height: AppSpacing.xs),
           _SidebarAccountTile(
             selected: accountSelected,
             onTap: onOpenAccount,
             name: accountName,
             subtitle: accountSubtitle,
           ),
+        ],
+      );
+    }
+
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.stretch,
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        Container(height: 1, color: palette.sidebarBorder),
+        const SizedBox(height: AppSpacing.xs),
+        _SidebarLanguageButton(
+          appLanguage: appLanguage,
+          compact: false,
+          onPressed: onToggleLanguage,
+        ),
+        const SizedBox(height: AppSpacing.xs),
+        Row(
+          children: [
+            Expanded(
+              child: _SidebarActionButton(
+                icon: themeMode == ThemeMode.dark
+                    ? Icons.dark_mode_rounded
+                    : themeMode == ThemeMode.light
+                    ? Icons.light_mode_rounded
+                    : Icons.brightness_auto_rounded,
+                label: appText('主题', 'Theme'),
+                onPressed: onOpenThemeToggle,
+              ),
+            ),
+            const SizedBox(width: AppSpacing.xs),
+            _SidebarActionButton(
+              icon: _sidebarStateIcon(sidebarState),
+              tooltip: _sidebarStateLabel(sidebarState),
+              onPressed: onCycleSidebarState,
+            ),
+          ],
+        ),
+        const SizedBox(height: AppSpacing.xs),
+        _SidebarAccountTile(
+          selected: accountSelected,
+          onTap: onOpenAccount,
+          name: accountName,
+          subtitle: accountSubtitle,
+        ),
       ],
     );
   }
+
+  IconData _sidebarStateIcon(AppSidebarState state) {
+    return switch (state) {
+      AppSidebarState.expanded => Icons.sidebar_rounded,
+      AppSidebarState.collapsed => Icons.menu_rounded,
+    };
+  }
+
+  String _sidebarStateLabel(AppSidebarState state) {
+    return switch (state) {
+      AppSidebarState.expanded => appText('收起侧边栏', 'Collapse sidebar'),
+      AppSidebarState.collapsed => appText('展开侧边栏', 'Expand sidebar'),
+    };
+  }
 }
 
-class _SidebarFooterActionTile extends StatefulWidget {
-  const _SidebarFooterActionTile({
+class _SidebarActionButton extends StatefulWidget {
+  const _SidebarActionButton({
     required this.icon,
-    required this.label,
-    required this.onTap,
+    this.label,
+    this.tooltip,
+    required this.onPressed,
     this.trailingText,
   });
 
   final IconData icon;
-  final String label;
-  final VoidCallback onTap;
+  final String? label;
+  final String? tooltip;
+  final VoidCallback onPressed;
   final String? trailingText;
 
   @override
-  State<_SidebarFooterActionTile> createState() =>
-      _SidebarFooterActionTileState();
+  State<_SidebarActionButton> createState() => _SidebarActionButtonState();
 }
 
-class _SidebarFooterActionTileState extends State<_SidebarFooterActionTile> {
+class _SidebarActionButtonState extends State<_SidebarActionButton> {
   bool _hovered = false;
 
   @override
   Widget build(BuildContext context) {
     final palette = context.palette;
+    final background = _hovered ? palette.hover : Colors.transparent;
 
-    return MouseRegion(
-      onEnter: (_) => setState(() => _hovered = true),
-      onExit: (_) => setState(() => _hovered = false),
-      child: Align(
-        alignment: Alignment.centerLeft,
+    if (widget.label != null) {
+      return MouseRegion(
+        onEnter: (_) => setState(() => _hovered = true),
+        onExit: (_) => setState(() => _hovered = false),
         child: AnimatedContainer(
           duration: const Duration(milliseconds: 160),
           decoration: BoxDecoration(
-            color: _hovered ? palette.hover : Colors.transparent,
-            borderRadius: BorderRadius.circular(10),
+            color: background,
+            borderRadius: BorderRadius.circular(AppRadius.button),
           ),
           child: Material(
             color: Colors.transparent,
             child: InkWell(
-              borderRadius: BorderRadius.circular(10),
-              onTap: widget.onTap,
-              child: Padding(
-                padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 8),
+              borderRadius: BorderRadius.circular(AppRadius.button),
+              onTap: widget.onPressed,
+              child: Container(
+                height: AppSizes.sidebarItemHeight,
+                padding: const EdgeInsets.symmetric(horizontal: AppSpacing.xs),
                 child: Row(
-                  mainAxisSize: MainAxisSize.min,
                   children: [
-                    Icon(widget.icon, size: 18, color: palette.textSecondary),
-                    const SizedBox(width: 8),
-                    Flexible(
-                      child: Text(
-                        widget.label,
-                        maxLines: 1,
-                        overflow: TextOverflow.ellipsis,
-                        style: Theme.of(context).textTheme.labelLarge,
-                      ),
+                    Icon(widget.icon, size: AppSizes.sidebarIconSize, color: palette.textSecondary),
+                    const SizedBox(width: AppSpacing.xs),
+                    Text(
+                      widget.label!,
+                      style: Theme.of(context).textTheme.labelLarge,
                     ),
                     if (widget.trailingText != null) ...[
-                      const SizedBox(width: 8),
+                      const Spacer(),
                       Text(
                         widget.trailingText!,
                         style: Theme.of(context).textTheme.bodySmall?.copyWith(
@@ -492,6 +472,35 @@ class _SidebarFooterActionTileState extends State<_SidebarFooterActionTile> {
             ),
           ),
         ),
+      );
+    }
+
+    return Tooltip(
+      message: widget.tooltip ?? '',
+      child: MouseRegion(
+        onEnter: (_) => setState(() => _hovered = true),
+        onExit: (_) => setState(() => _hovered = false),
+        child: AnimatedContainer(
+          duration: const Duration(milliseconds: 160),
+          decoration: BoxDecoration(
+            color: background,
+            borderRadius: BorderRadius.circular(AppRadius.button),
+          ),
+          child: Material(
+            color: Colors.transparent,
+            child: InkWell(
+              borderRadius: BorderRadius.circular(AppRadius.button),
+              onTap: widget.onPressed,
+              child: Container(
+                height: AppSizes.sidebarItemHeight,
+                padding: const EdgeInsets.symmetric(horizontal: AppSpacing.xs),
+                child: Center(
+                  child: Icon(widget.icon, size: AppSizes.sidebarIconSize, color: palette.textSecondary),
+                ),
+              ),
+            ),
+          ),
+        ),
       ),
     );
   }
@@ -535,27 +544,28 @@ class _SidebarAccountTileState extends State<_SidebarAccountTile> {
           duration: const Duration(milliseconds: 160),
           decoration: BoxDecoration(
             color: background,
-            borderRadius: BorderRadius.circular(10),
+            borderRadius: BorderRadius.circular(AppRadius.button),
           ),
           child: Material(
             color: Colors.transparent,
             child: InkWell(
-              borderRadius: BorderRadius.circular(10),
+              borderRadius: BorderRadius.circular(AppRadius.button),
               onTap: widget.onTap,
-              child: Padding(
-                padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 8),
+              child: Container(
+                height: AppSizes.sidebarItemHeight,
+                padding: const EdgeInsets.symmetric(horizontal: AppSpacing.xs),
                 child: Row(
                   mainAxisSize: MainAxisSize.max,
                   children: [
                     CircleAvatar(
-                      radius: 16,
+                      radius: 14,
                       child: Text(
                         widget.name.trim().isEmpty
                             ? 'X'
                             : widget.name.trim().substring(0, 1).toUpperCase(),
                       ),
                     ),
-                    const SizedBox(width: 8),
+                    const SizedBox(width: AppSpacing.xs),
                     Expanded(
                       child: Column(
                         crossAxisAlignment: CrossAxisAlignment.start,
@@ -609,13 +619,13 @@ class _SidebarLanguageButtonState extends State<_SidebarLanguageButton> {
   @override
   Widget build(BuildContext context) {
     final palette = context.palette;
-    final size = widget.compact ? 36.0 : 44.0;
+    final size = widget.compact ? AppSizes.sidebarItemHeight : 44.0;
 
     return MouseRegion(
       onEnter: (_) => setState(() => _hovered = true),
       onExit: (_) => setState(() => _hovered = false),
       child: InkWell(
-        borderRadius: BorderRadius.circular(10),
+        borderRadius: BorderRadius.circular(AppRadius.button),
         onTap: widget.onPressed,
         child: AnimatedContainer(
           duration: const Duration(milliseconds: 160),
@@ -624,7 +634,7 @@ class _SidebarLanguageButtonState extends State<_SidebarLanguageButton> {
           alignment: Alignment.center,
           decoration: BoxDecoration(
             color: _hovered ? palette.hover : palette.surfaceSecondary,
-            borderRadius: BorderRadius.circular(10),
+            borderRadius: BorderRadius.circular(AppRadius.button),
             border: Border.all(color: palette.strokeSoft),
           ),
           child: Text(
diff --git a/lib/widgets/status_badge.dart b/lib/widgets/status_badge.dart
index 3350e587..cfa9a326 100644
--- a/lib/widgets/status_badge.dart
+++ b/lib/widgets/status_badge.dart
@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 
 import '../models/app_models.dart';
 import '../theme/app_palette.dart';
+import '../theme/app_theme.dart';
 
 class StatusBadge extends StatelessWidget {
   const StatusBadge({super.key, required this.status, this.compact = false});
@@ -31,12 +32,12 @@ class StatusBadge extends StatelessWidget {
 
     return Container(
       padding: EdgeInsets.symmetric(
-        horizontal: compact ? 8 : 10,
+        horizontal: compact ? AppSpacing.xs : 10,
         vertical: compact ? 4 : 6,
       ),
       decoration: BoxDecoration(
         color: tone.$1,
-        borderRadius: BorderRadius.circular(10),
+        borderRadius: BorderRadius.circular(AppRadius.badge),
       ),
       child: Text(
         status.label,
diff --git a/lib/widgets/surface_card.dart b/lib/widgets/surface_card.dart
index a5e23292..9d9ccbf6 100644
--- a/lib/widgets/surface_card.dart
+++ b/lib/widgets/surface_card.dart
@@ -1,14 +1,15 @@
 import 'package:flutter/material.dart';
 
 import '../theme/app_palette.dart';
+import '../theme/app_theme.dart';
 
 class SurfaceCard extends StatefulWidget {
   const SurfaceCard({
     super.key,
     required this.child,
-    this.padding = const EdgeInsets.all(16),
+    this.padding = const EdgeInsets.all(AppSpacing.md),
     this.onTap,
-    this.borderRadius = 16,
+    this.borderRadius = AppRadius.card,
     this.color,
   });
 
diff --git a/lib/widgets/top_bar.dart b/lib/widgets/top_bar.dart
index 18d584ab..cfba13c7 100644
--- a/lib/widgets/top_bar.dart
+++ b/lib/widgets/top_bar.dart
@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import '../theme/app_theme.dart';
 
 class TopBar extends StatelessWidget {
   const TopBar({
@@ -23,9 +24,9 @@ class TopBar extends StatelessWidget {
             crossAxisAlignment: CrossAxisAlignment.start,
             children: [
               Text(title, style: Theme.of(context).textTheme.headlineSmall),
-              const SizedBox(height: 8),
+              const SizedBox(height: AppSpacing.xs),
               Text(subtitle, style: Theme.of(context).textTheme.bodyMedium),
-              if (trailing != null) ...[const SizedBox(height: 16), trailing!],
+              if (trailing != null) ...[const SizedBox(height: AppSpacing.md), trailing!],
             ],
           );
         }
@@ -38,13 +39,13 @@ class TopBar extends StatelessWidget {
                 crossAxisAlignment: CrossAxisAlignment.start,
                 children: [
                   Text(title, style: Theme.of(context).textTheme.headlineSmall),
-                  const SizedBox(height: 8),
+                  const SizedBox(height: AppSpacing.xs),
                   Text(subtitle, style: Theme.of(context).textTheme.bodyMedium),
                 ],
               ),
             ),
             if (trailing != null) ...[
-              const SizedBox(width: 24),
+              const SizedBox(width: AppSpacing.lg),
               Flexible(child: trailing!),
             ],
           ],