diff --git a/lib/main.dart b/lib/main.dart
index 495810d..e98aaff 100644
--- a/lib/main.dart
+++ b/lib/main.dart
@@ -73,7 +73,7 @@ class MyApp extends StatelessWidget {
               panEnabled: false,
               scaleEnabled: true,
               minScale: 0.8,
-              maxScale: 2.0,
+              maxScale: 4.0,
               child: child ?? const SizedBox.shrink(),
             ),
           ),
diff --git a/lib/screens/customer_master_screen.dart b/lib/screens/customer_master_screen.dart
index bdea89f..76a01da 100644
--- a/lib/screens/customer_master_screen.dart
+++ b/lib/screens/customer_master_screen.dart
@@ -416,6 +416,7 @@ class _CustomerMasterScreenState extends State<CustomerMasterScreen> {
                       department: departmentController.text.isEmpty ? null : departmentController.text,
                       address: addressController.text.isEmpty ? null : addressController.text,
                       tel: telController.text.isEmpty ? null : telController.text,
+                      email: emailController.text.isEmpty ? null : emailController.text,
                       headChar1: head1.isEmpty ? _headKana(displayNameController.text) : head1,
                       headChar2: head2.isEmpty ? null : head2,
                       isLocked: customer?.isLocked ?? false,
diff --git a/lib/screens/invoice_detail_page.dart b/lib/screens/invoice_detail_page.dart
index 9574e48..a608d59 100644
--- a/lib/screens/invoice_detail_page.dart
+++ b/lib/screens/invoice_detail_page.dart
@@ -13,6 +13,36 @@ import 'product_picker_modal.dart';
 import '../models/company_model.dart';
 import '../widgets/keyboard_inset_wrapper.dart';
 
+class _DetailSnapshot {
+  final String formalName;
+  final String notes;
+  final List<InvoiceItem> items;
+  final double taxRate;
+  final bool includeTax;
+  final bool isDraft;
+
+  const _DetailSnapshot({
+    required this.formalName,
+    required this.notes,
+    required this.items,
+    required this.taxRate,
+    required this.includeTax,
+    required this.isDraft,
+  });
+}
+
+List<InvoiceItem> _cloneItemsDetail(List<InvoiceItem> source) {
+  return source
+      .map((e) => InvoiceItem(
+            id: e.id,
+            productId: e.productId,
+            description: e.description,
+            quantity: e.quantity,
+            unitPrice: e.unitPrice,
+          ))
+      .toList(growable: true);
+}
+
 class InvoiceDetailPage extends StatefulWidget {
   final Invoice invoice;
   final bool editable;
@@ -38,6 +68,9 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
   final _companyRepo = CompanyRepository();
   CompanyInfo? _companyInfo;
   bool _showFormalWarning = true;
+  final List<_DetailSnapshot> _undoStack = [];
+  final List<_DetailSnapshot> _redoStack = [];
+  bool _isApplyingSnapshot = false;
 
   @override
   void initState() {
@@ -69,12 +102,14 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
     setState(() {
       _items.add(InvoiceItem(description: "新項目", quantity: 1, unitPrice: 0));
     });
+    _pushHistory();
   }
 
   void _removeItem(int index) {
     setState(() {
       _items.removeAt(index);
     });
+    _pushHistory();
   }
 
   void _pickFromMaster() {
@@ -126,6 +161,8 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
     }
 
     setState(() => _isEditing = false);
+    _undoStack.clear();
+    _redoStack.clear();
 
     final newPath = await generateInvoicePdf(updatedInvoice);
     if (newPath != null) {
@@ -153,6 +190,7 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
   Widget build(BuildContext context) {
     final fmt = NumberFormat("#,###");
     final isDraft = _currentInvoice.isDraft;
+    final docTypeName = _currentInvoice.documentTypeName;
     final themeColor = Colors.white; // 常に明色
     final textColor = Colors.black87;
 
@@ -163,26 +201,7 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
       resizeToAvoidBottomInset: false,
       appBar: AppBar(
         leading: const BackButton(), // 常に表示
-        title: Row(
-          mainAxisSize: MainAxisSize.min,
-          children: [
-            Flexible(
-              child: Text(
-                isDraft ? "A3:伝票詳細" : "A3:伝票詳細",
-                overflow: TextOverflow.ellipsis,
-              ),
-            ),
-            const SizedBox(width: 8),
-            if (isDraft)
-              Chip(
-                label: const Text("下書き", style: TextStyle(color: Colors.white)),
-                backgroundColor: Colors.orange,
-                padding: EdgeInsets.zero,
-                materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
-                visualDensity: VisualDensity.compact,
-              ),
-          ],
-        ),
+        title: const Text("A3:伝票詳細"),
         backgroundColor: Colors.indigo.shade700,
         actions: [
           if (locked)
@@ -226,6 +245,7 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
               onPressed: (locked || !widget.isUnlocked)
                   ? null
                   : () async {
+                      _pushHistory(clearRedo: true);
                       await Navigator.push(
                         context,
                         MaterialPageRoute(
@@ -243,6 +263,16 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
                     },
             ),
           ] else ...[
+            IconButton(
+              icon: const Icon(Icons.undo),
+              onPressed: _undoStack.isNotEmpty ? _undo : null,
+              tooltip: "元に戻す",
+            ),
+            IconButton(
+              icon: const Icon(Icons.redo),
+              onPressed: _redoStack.isNotEmpty ? _redo : null,
+              tooltip: "やり直す",
+            ),
             IconButton(icon: const Icon(Icons.save), onPressed: _saveChanges),
             IconButton(icon: const Icon(Icons.cancel), onPressed: () => setState(() => _isEditing = false)),
           ]
@@ -259,21 +289,33 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
               if (isDraft)
                 Container(
                   width: double.infinity,
-                  padding: const EdgeInsets.all(8),
+                  padding: const EdgeInsets.all(10),
                   margin: const EdgeInsets.only(bottom: 8),
                   decoration: BoxDecoration(
-                    color: Colors.orange.shade50,
+                    color: Colors.indigo.shade800,
                     borderRadius: BorderRadius.circular(8),
-                    border: Border.all(color: Colors.orange.shade200),
+                    border: Border.all(color: Colors.indigo.shade900),
                   ),
                   child: Row(
-                    children: const [
-                      Icon(Icons.edit_note, color: Colors.orange),
-                      SizedBox(width: 8),
+                    children: [
+                      const Icon(Icons.edit_note, color: Colors.white70),
+                      const SizedBox(width: 8),
                       Expanded(
                         child: Text(
                           "下書き: 未確定・PDFは正式発行で確定",
-                          style: TextStyle(color: Colors.orange),
+                          style: const TextStyle(color: Colors.white70),
+                        ),
+                      ),
+                      const SizedBox(width: 8),
+                      Container(
+                        padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 4),
+                        decoration: BoxDecoration(
+                          color: Colors.orange.shade600,
+                          borderRadius: BorderRadius.circular(16),
+                        ),
+                        child: Text(
+                          "下書${docTypeName}",
+                          style: const TextStyle(color: Colors.white, fontWeight: FontWeight.bold, fontSize: 12),
                         ),
                       ),
                     ],
@@ -332,12 +374,14 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
         if (_isEditing) ...[
           TextField(
             controller: _formalNameController,
+            onChanged: (_) => _pushHistory(),
             decoration: const InputDecoration(labelText: "取引先 正式名称", border: OutlineInputBorder()),
             style: TextStyle(color: textColor),
           ),
           const SizedBox(height: 12),
           TextField(
             controller: _notesController,
+            onChanged: (_) => _pushHistory(),
             maxLines: 2,
             decoration: const InputDecoration(labelText: "備考", border: OutlineInputBorder()),
             style: TextStyle(color: textColor),
@@ -350,17 +394,6 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
                 "伝票番号: ${_currentInvoice.invoiceNumber}",
                 style: TextStyle(fontSize: 16, fontWeight: FontWeight.bold, color: textColor),
               ),
-              Container(
-                padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 4),
-                decoration: BoxDecoration(
-                  color: _currentInvoice.isDraft ? Colors.orange : Colors.green.shade700,
-                  borderRadius: BorderRadius.circular(20),
-                ),
-                child: Text(
-                  _currentInvoice.isDraft ? "下書き" : "確定済",
-                  style: const TextStyle(color: Colors.white, fontSize: 12, fontWeight: FontWeight.bold),
-                ),
-              ),
             ],
           ),
           const SizedBox(height: 8),
@@ -369,29 +402,43 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
             style: TextStyle(color: textColor.withAlpha((0.8 * 255).round())),
           ),
           const SizedBox(height: 8),
-          Text("取引先:", style: TextStyle(fontWeight: FontWeight.bold, color: textColor)),
-          Text("${_currentInvoice.customerNameForDisplay} ${_currentInvoice.customer.title}",
-              style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold, color: textColor)),
-          if (_currentInvoice.subject?.isNotEmpty ?? false) ...[
-            const SizedBox(height: 8),
-            Text("件名: ${_currentInvoice.subject}",
-                style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold, color: Colors.indigoAccent)),
-          ],
-          if (_currentInvoice.customer.department != null && _currentInvoice.customer.department!.isNotEmpty)
-            Text(_currentInvoice.customer.department!, style: TextStyle(fontSize: 16, color: textColor)),
-          if ((_currentInvoice.contactAddressSnapshot ?? _currentInvoice.customer.address) != null)
-            Text("住所: ${_currentInvoice.contactAddressSnapshot ?? _currentInvoice.customer.address}", style: TextStyle(color: textColor)),
-          if ((_currentInvoice.contactTelSnapshot ?? _currentInvoice.customer.tel) != null)
-            Text("TEL: ${_currentInvoice.contactTelSnapshot ?? _currentInvoice.customer.tel}", style: TextStyle(color: textColor)),
-          if ((_currentInvoice.contactEmailSnapshot ?? _currentInvoice.customer.email) != null)
-            Text("メール: ${_currentInvoice.contactEmailSnapshot ?? _currentInvoice.customer.email}", style: TextStyle(color: textColor)),
-          if (_currentInvoice.notes?.isNotEmpty ?? false) ...[
-            const SizedBox(height: 8),
-            Text(
-              "備考: ${_currentInvoice.notes}",
-              style: TextStyle(color: textColor.withAlpha((0.9 * 255).round())),
+          Container(
+            width: double.infinity,
+            padding: const EdgeInsets.all(12),
+            decoration: BoxDecoration(
+              color: Colors.grey.shade100,
+              borderRadius: BorderRadius.circular(12),
             ),
-          ],
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: [
+                Text("取引先", style: TextStyle(fontWeight: FontWeight.bold, color: textColor)),
+                const SizedBox(height: 4),
+                Text("${_currentInvoice.customerNameForDisplay} ${_currentInvoice.customer.title}",
+                    style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold, color: textColor)),
+                if (_currentInvoice.subject?.isNotEmpty ?? false) ...[
+                  const SizedBox(height: 6),
+                  Text("件名: ${_currentInvoice.subject}",
+                      style: TextStyle(fontSize: 16, fontWeight: FontWeight.bold, color: Colors.indigo)),
+                ],
+                if (_currentInvoice.customer.department != null && _currentInvoice.customer.department!.isNotEmpty)
+                  Text(_currentInvoice.customer.department!, style: TextStyle(fontSize: 14, color: textColor)),
+                if ((_currentInvoice.contactAddressSnapshot ?? _currentInvoice.customer.address) != null)
+                  Text("住所: ${_currentInvoice.contactAddressSnapshot ?? _currentInvoice.customer.address}", style: TextStyle(color: textColor)),
+                if ((_currentInvoice.contactTelSnapshot ?? _currentInvoice.customer.tel) != null)
+                  Text("TEL: ${_currentInvoice.contactTelSnapshot ?? _currentInvoice.customer.tel}", style: TextStyle(color: textColor)),
+                if ((_currentInvoice.contactEmailSnapshot ?? _currentInvoice.customer.email) != null)
+                  Text("メール: ${_currentInvoice.contactEmailSnapshot ?? _currentInvoice.customer.email}", style: TextStyle(color: textColor)),
+                if (_currentInvoice.notes?.isNotEmpty ?? false) ...[
+                  const SizedBox(height: 6),
+                  Text(
+                    "備考: ${_currentInvoice.notes}",
+                    style: TextStyle(color: textColor.withAlpha((0.9 * 255).round())),
+                  ),
+                ],
+              ],
+            ),
+          ),
         ],
       ],
     );
@@ -427,19 +474,28 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
               _EditableCell(
                 initialValue: item.description,
                 textColor: textColor,
-                onChanged: (val) => item.description = val,
+                onChanged: (val) {
+                  setState(() => item.description = val);
+                  _pushHistory();
+                },
               ),
               _EditableCell(
                 initialValue: item.quantity.toString(),
                 textColor: textColor,
                 keyboardType: TextInputType.number,
-                onChanged: (val) => setState(() => item.quantity = int.tryParse(val) ?? 0),
+                onChanged: (val) {
+                  setState(() => item.quantity = int.tryParse(val) ?? 0);
+                  _pushHistory();
+                },
               ),
               _EditableCell(
                 initialValue: item.unitPrice.toString(),
                 textColor: textColor,
                 keyboardType: TextInputType.number,
-                onChanged: (val) => setState(() => item.unitPrice = int.tryParse(val) ?? 0),
+                onChanged: (val) {
+                  setState(() => item.unitPrice = int.tryParse(val) ?? 0);
+                  _pushHistory();
+                },
               ),
               _TableCell(formatter.format(item.subtotal), textColor: textColor),
               IconButton(icon: const Icon(Icons.delete, size: 20, color: Colors.red), onPressed: () => _removeItem(idx)),
@@ -468,7 +524,7 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
       width: double.infinity,
       padding: const EdgeInsets.all(16),
       decoration: BoxDecoration(
-        color: Colors.indigo.shade900,
+        color: Colors.indigo,
         borderRadius: BorderRadius.circular(12),
       ),
       child: Column(
@@ -525,6 +581,61 @@ class _InvoiceDetailPageState extends State<InvoiceDetailPage> {
     return _items.fold(0, (sum, item) => sum + (item.quantity * item.unitPrice));
   }
 
+  void _pushHistory({bool clearRedo = false}) {
+    if (!_isEditing || _isApplyingSnapshot) return;
+    if (_undoStack.length >= 30) _undoStack.removeAt(0);
+    _undoStack.add(_DetailSnapshot(
+      formalName: _formalNameController.text,
+      notes: _notesController.text,
+      items: _cloneItemsDetail(_items),
+      taxRate: _taxRate,
+      includeTax: _includeTax,
+      isDraft: _currentInvoice.isDraft,
+    ));
+    if (clearRedo) _redoStack.clear();
+    setState(() {});
+  }
+
+  void _undo() {
+    if (_undoStack.isEmpty) return;
+    final snapshot = _undoStack.removeLast();
+    _redoStack.add(_DetailSnapshot(
+      formalName: _formalNameController.text,
+      notes: _notesController.text,
+      items: _cloneItemsDetail(_items),
+      taxRate: _taxRate,
+      includeTax: _includeTax,
+      isDraft: _currentInvoice.isDraft,
+    ));
+    _applySnapshot(snapshot);
+  }
+
+  void _redo() {
+    if (_redoStack.isEmpty) return;
+    final snapshot = _redoStack.removeLast();
+    _undoStack.add(_DetailSnapshot(
+      formalName: _formalNameController.text,
+      notes: _notesController.text,
+      items: _cloneItemsDetail(_items),
+      taxRate: _taxRate,
+      includeTax: _includeTax,
+      isDraft: _currentInvoice.isDraft,
+    ));
+    _applySnapshot(snapshot);
+  }
+
+  void _applySnapshot(_DetailSnapshot snapshot) {
+    _isApplyingSnapshot = true;
+    setState(() {
+      _formalNameController.text = snapshot.formalName;
+      _notesController.text = snapshot.notes;
+      _items = _cloneItemsDetail(snapshot.items);
+      _taxRate = snapshot.taxRate;
+      _includeTax = snapshot.includeTax;
+    });
+    _isApplyingSnapshot = false;
+  }
+
   Widget _buildExperimentalSection(bool isDraft) {
     return Container(
       padding: const EdgeInsets.all(12),
diff --git a/lib/screens/invoice_input_screen.dart b/lib/screens/invoice_input_screen.dart
index 5809ea0..bd018e6 100644
--- a/lib/screens/invoice_input_screen.dart
+++ b/lib/screens/invoice_input_screen.dart
@@ -28,6 +28,18 @@ class InvoiceInputForm extends StatefulWidget {
   State<InvoiceInputForm> createState() => _InvoiceInputFormState();
 }
 
+List<InvoiceItem> _cloneItems(List<InvoiceItem> source) {
+  return source
+      .map((e) => InvoiceItem(
+            id: e.id,
+            productId: e.productId,
+            description: e.description,
+            quantity: e.quantity,
+            unitPrice: e.unitPrice,
+          ))
+      .toList(growable: true);
+}
+
 class _InvoiceInputFormState extends State<InvoiceInputForm> {
   final _repository = InvoiceRepository();
   final InvoiceRepository _invoiceRepo = InvoiceRepository();
@@ -40,24 +52,34 @@ class _InvoiceInputFormState extends State<InvoiceInputForm> {
   bool _isDraft = true; // デフォルトは下書き
   final TextEditingController _subjectController = TextEditingController(); // 追加
   bool _isSaving = false; // 保存中フラグ
-  
+  final List<_InvoiceSnapshot> _undoStack = [];
+  final List<_InvoiceSnapshot> _redoStack = [];
+  bool _isApplyingSnapshot = false;
+  bool get _canUndo => _undoStack.length > 1;
+  bool get _canRedo => _redoStack.isNotEmpty;
+
   // 署名用の実験的パス
   final List<Offset?> _signaturePath = [];
 
   @override
   void initState() {
     super.initState();
+    _subjectController.addListener(_onSubjectChanged);
     _loadInitialData();
   }
 
+  @override
+  void dispose() {
+    _subjectController.removeListener(_onSubjectChanged);
+    _subjectController.dispose();
+    super.dispose();
+  }
+
   Future<void> _loadInitialData() async {
     _repository.cleanupOrphanedPdfs();
     final customerRepo = CustomerRepository();
-    final customers = await customerRepo.getAllCustomers();
-    if (customers.isNotEmpty) {
-      setState(() => _selectedCustomer = customers.first);
-    }
-    
+    await customerRepo.getAllCustomers();
+
     setState(() {
       // 既存伝票がある場合は初期値を上書き
       if (widget.existingInvoice != null) {
@@ -77,6 +99,12 @@ class _InvoiceInputFormState extends State<InvoiceInputForm> {
         _documentType = widget.initialDocumentType;
       }
     });
+    _pushHistory(clearRedo: true);
+  }
+
+  void _onSubjectChanged() {
+    if (_isApplyingSnapshot) return;
+    _pushHistory();
   }
 
   void _addItem() {
@@ -93,6 +121,7 @@ class _InvoiceInputFormState extends State<InvoiceInputForm> {
           unitPrice: product.defaultUnitPrice,
         ));
       });
+      _pushHistory();
     });
   }
 
@@ -207,6 +236,84 @@ class _InvoiceInputFormState extends State<InvoiceInputForm> {
     );
   }
 
+  void _pushHistory({bool clearRedo = false}) {
+    setState(() {
+      if (_undoStack.length >= 30) _undoStack.removeAt(0);
+      _undoStack.add(_InvoiceSnapshot(
+        customer: _selectedCustomer,
+        items: _cloneItems(_items),
+        taxRate: _taxRate,
+        includeTax: _includeTax,
+        documentType: _documentType,
+        date: _selectedDate,
+        isDraft: _isDraft,
+        subject: _subjectController.text,
+      ));
+      if (clearRedo) _redoStack.clear();
+    });
+  }
+
+  void _undo() {
+    if (_undoStack.length <= 1) return; // 直前状態がない
+    setState(() {
+      // 現在の状態をredoへ積む
+      _redoStack.add(_InvoiceSnapshot(
+        customer: _selectedCustomer,
+        items: _cloneItems(_items),
+        taxRate: _taxRate,
+        includeTax: _includeTax,
+        documentType: _documentType,
+        date: _selectedDate,
+        isDraft: _isDraft,
+        subject: _subjectController.text,
+      ));
+      // 一番新しい履歴を捨て、直前のスナップショットを適用
+      _undoStack.removeLast();
+      final snapshot = _undoStack.last;
+      _isApplyingSnapshot = true;
+      _selectedCustomer = snapshot.customer;
+      _items
+        ..clear()
+        ..addAll(_cloneItems(snapshot.items));
+      _taxRate = snapshot.taxRate;
+      _includeTax = snapshot.includeTax;
+      _documentType = snapshot.documentType;
+      _selectedDate = snapshot.date;
+      _isDraft = snapshot.isDraft;
+      _subjectController.text = snapshot.subject;
+      _isApplyingSnapshot = false;
+    });
+  }
+
+  void _redo() {
+    if (_redoStack.isEmpty) return;
+    setState(() {
+      _undoStack.add(_InvoiceSnapshot(
+        customer: _selectedCustomer,
+        items: _cloneItems(_items),
+        taxRate: _taxRate,
+        includeTax: _includeTax,
+        documentType: _documentType,
+        date: _selectedDate,
+        isDraft: _isDraft,
+        subject: _subjectController.text,
+      ));
+      final snapshot = _redoStack.removeLast();
+      _isApplyingSnapshot = true;
+      _selectedCustomer = snapshot.customer;
+      _items
+        ..clear()
+        ..addAll(_cloneItems(snapshot.items));
+      _taxRate = snapshot.taxRate;
+      _includeTax = snapshot.includeTax;
+      _documentType = snapshot.documentType;
+      _selectedDate = snapshot.date;
+      _isDraft = snapshot.isDraft;
+      _subjectController.text = snapshot.subject;
+      _isApplyingSnapshot = false;
+    });
+  }
+
   @override
   Widget build(BuildContext context) {
     final fmt = NumberFormat("#,###");
@@ -219,6 +326,18 @@ class _InvoiceInputFormState extends State<InvoiceInputForm> {
       appBar: AppBar(
         leading: const BackButton(),
         title: const Text("A1:伝票入力"),
+        actions: [
+          IconButton(
+            icon: const Icon(Icons.undo),
+            onPressed: _canUndo ? _undo : null,
+            tooltip: "元に戻す",
+          ),
+          IconButton(
+            icon: const Icon(Icons.redo),
+            onPressed: _canRedo ? _redo : null,
+            tooltip: "やり直す",
+          ),
+        ],
       ),
       body: Stack(
         children: [
@@ -281,6 +400,7 @@ class _InvoiceInputFormState extends State<InvoiceInputForm> {
         );
         if (picked != null) {
           setState(() => _selectedDate = picked);
+          _pushHistory();
         }
       },
       child: Container(
@@ -324,6 +444,7 @@ class _InvoiceInputFormState extends State<InvoiceInputForm> {
           );
           if (picked != null) {
             setState(() => _selectedCustomer = picked);
+            _pushHistory();
           }
         },
       ),
@@ -357,6 +478,7 @@ class _InvoiceInputFormState extends State<InvoiceInputForm> {
                 final item = _items.removeAt(oldIndex);
                 _items.insert(newIndex, item);
               });
+              _pushHistory();
             },
             buildDefaultDragHandles: false,
             itemBuilder: (context, idx) {
@@ -376,56 +498,72 @@ class _InvoiceInputFormState extends State<InvoiceInputForm> {
                         const SizedBox(width: 8),
                         IconButton(
                           icon: const Icon(Icons.remove_circle_outline, color: Colors.redAccent),
-                          onPressed: () => setState(() => _items.removeAt(idx)),
+                          onPressed: () {
+                            setState(() => _items.removeAt(idx));
+                            _pushHistory();
+                          },
                           tooltip: "削除",
                         ),
                       ],
                     ),
                     onTap: () {
-                      // 簡易編集ダイアログ
+                      // 簡易編集ダイアログ（キーボードでせり上げない）
                       final descCtrl = TextEditingController(text: item.description);
                       final qtyCtrl = TextEditingController(text: item.quantity.toString());
                       final priceCtrl = TextEditingController(text: item.unitPrice.toString());
                       showDialog(
                         context: context,
-                        builder: (context) => AlertDialog(
-                          title: const Text("明細の編集"),
-                          content: Column(
-                            mainAxisSize: MainAxisSize.min,
-                            children: [
-                              TextField(controller: descCtrl, decoration: const InputDecoration(labelText: "品名 / 項目")),
-                              TextField(controller: qtyCtrl, decoration: const InputDecoration(labelText: "数量"), keyboardType: TextInputType.number),
-                              TextField(controller: priceCtrl, decoration: const InputDecoration(labelText: "単価"), keyboardType: TextInputType.number),
-                            ],
-                          ),
-                          actions: [
-                            TextButton.icon(
-                              icon: const Icon(Icons.search, size: 18),
-                              label: const Text("マスター参照"),
-                              onPressed: () async {
-                                Navigator.pop(context); // close edit dialog before jumping
-                                await Navigator.push(
-                                  this.context,
-                                  MaterialPageRoute(builder: (_) => const ProductMasterScreen()),
-                                );
-                              },
+                        builder: (context) {
+                          final inset = MediaQuery.of(context).viewInsets.bottom;
+                          return MediaQuery.removeViewInsets(
+                            removeBottom: true,
+                            context: context,
+                            child: AlertDialog(
+                              insetPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 24),
+                              title: const Text("明細の編集"),
+                              content: SingleChildScrollView(
+                                padding: EdgeInsets.only(bottom: inset + 12),
+                                keyboardDismissBehavior: ScrollViewKeyboardDismissBehavior.onDrag,
+                                child: Column(
+                                  mainAxisSize: MainAxisSize.min,
+                                  children: [
+                                    TextField(controller: descCtrl, decoration: const InputDecoration(labelText: "品名 / 項目")),
+                                    TextField(controller: qtyCtrl, decoration: const InputDecoration(labelText: "数量"), keyboardType: TextInputType.number),
+                                    TextField(controller: priceCtrl, decoration: const InputDecoration(labelText: "単価"), keyboardType: TextInputType.number),
+                                  ],
+                                ),
+                              ),
+                              actions: [
+                                TextButton.icon(
+                                  icon: const Icon(Icons.search, size: 18),
+                                  label: const Text("マスター参照"),
+                                  onPressed: () async {
+                                    Navigator.pop(context); // close edit dialog before jumping
+                                    await Navigator.push(
+                                      this.context,
+                                      MaterialPageRoute(builder: (_) => const ProductMasterScreen()),
+                                    );
+                                  },
+                                ),
+                                TextButton(onPressed: () => Navigator.pop(context), child: const Text("キャンセル")),
+                                ElevatedButton(
+                                  onPressed: () {
+                                    setState(() {
+                                      _items[idx] = item.copyWith(
+                                        description: descCtrl.text,
+                                        quantity: int.tryParse(qtyCtrl.text) ?? item.quantity,
+                                        unitPrice: int.tryParse(priceCtrl.text) ?? item.unitPrice,
+                                      );
+                                    });
+                                    _pushHistory();
+                                    Navigator.pop(context);
+                                  },
+                                  child: const Text("更新"),
+                                ),
+                              ],
                             ),
-                            TextButton(onPressed: () => Navigator.pop(context), child: const Text("キャンセル")),
-                            ElevatedButton(
-                              onPressed: () {
-                                setState(() {
-                                  _items[idx] = item.copyWith(
-                                    description: descCtrl.text,
-                                    quantity: int.tryParse(qtyCtrl.text) ?? item.quantity,
-                                    unitPrice: int.tryParse(priceCtrl.text) ?? item.unitPrice,
-                                  );
-                                });
-                                Navigator.pop(context);
-                              },
-                              child: const Text("更新"),
-                            ),
-                          ],
-                        ),
+                          );
+                        },
                       );
                     },
                   ),
@@ -446,7 +584,7 @@ class _InvoiceInputFormState extends State<InvoiceInputForm> {
       width: double.infinity,
       padding: const EdgeInsets.all(16),
       decoration: BoxDecoration(
-        color: Colors.indigo.shade900,
+        color: Colors.indigo,
         borderRadius: BorderRadius.circular(12),
       ),
       child: Column(
@@ -584,16 +722,23 @@ class _InvoiceInputFormState extends State<InvoiceInputForm> {
       children: [
         Text("案件名 / 件名", style: TextStyle(fontWeight: FontWeight.bold, color: textColor)),
         const SizedBox(height: 8),
-        TextField(
-          controller: _subjectController,
-          style: TextStyle(color: textColor),
-          decoration: InputDecoration(
-            hintText: "例：事務所改修工事 / 〇〇月分リース料",
-            hintStyle: TextStyle(color: textColor.withAlpha((0.5 * 255).round())),
-            filled: true,
-            fillColor: _isDraft ? Colors.white12 : Colors.grey.shade100,
-            border: OutlineInputBorder(borderRadius: BorderRadius.circular(12), borderSide: BorderSide.none),
-            contentPadding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
+        Container(
+          width: double.infinity,
+          padding: const EdgeInsets.all(12),
+          decoration: BoxDecoration(
+            color: Colors.grey.shade100,
+            borderRadius: BorderRadius.circular(12),
+          ),
+          child: TextField(
+            controller: _subjectController,
+            style: TextStyle(color: textColor),
+            decoration: InputDecoration(
+              hintText: "例：事務所改修工事 / 〇〇月分リース料",
+              hintStyle: TextStyle(color: textColor.withAlpha((0.5 * 255).round())),
+              border: InputBorder.none,
+              isDense: true,
+              contentPadding: const EdgeInsets.symmetric(horizontal: 4, vertical: 4),
+            ),
           ),
         ),
       ],
@@ -601,6 +746,28 @@ class _InvoiceInputFormState extends State<InvoiceInputForm> {
   }
 }
 
+class _InvoiceSnapshot {
+  final Customer? customer;
+  final List<InvoiceItem> items;
+  final double taxRate;
+  final bool includeTax;
+  final DocumentType documentType;
+  final DateTime date;
+  final bool isDraft;
+  final String subject;
+
+  _InvoiceSnapshot({
+    required this.customer,
+    required this.items,
+    required this.taxRate,
+    required this.includeTax,
+    required this.documentType,
+    required this.date,
+    required this.isDraft,
+    required this.subject,
+  });
+}
+
 class SignaturePainter extends CustomPainter {
   final List<Offset?> points;
   SignaturePainter(this.points);
diff --git a/lib/screens/settings_screen.dart b/lib/screens/settings_screen.dart
index 2f42080..652fbe1 100644
--- a/lib/screens/settings_screen.dart
+++ b/lib/screens/settings_screen.dart
@@ -232,6 +232,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
       resizeToAvoidBottomInset: false,
       appBar: AppBar(
         title: const Text('S1:設定'),
+        backgroundColor: Colors.indigo,
         actions: [
           IconButton(
             icon: const Icon(Icons.info_outline),
@@ -246,6 +247,38 @@ class _SettingsScreenState extends State<SettingsScreen> {
           physics: const AlwaysScrollableScrollPhysics(),
           padding: EdgeInsets.only(bottom: listBottomPadding),
           children: [
+            Container(
+              width: double.infinity,
+              padding: const EdgeInsets.all(14),
+              margin: const EdgeInsets.only(bottom: 16),
+              decoration: BoxDecoration(
+                color: Colors.indigo.shade50,
+                borderRadius: BorderRadius.circular(12),
+                border: Border.all(color: Colors.indigo.shade100),
+              ),
+              child: Row(
+                children: [
+                  const Icon(Icons.business, color: Colors.indigo, size: 28),
+                  const SizedBox(width: 12),
+                  const Expanded(
+                    child: Text(
+                      "自社情報を開く",
+                      style: TextStyle(fontWeight: FontWeight.bold, color: Colors.indigo),
+                    ),
+                  ),
+                  ElevatedButton.icon(
+                    onPressed: () => Navigator.push(context, MaterialPageRoute(builder: (_) => const CompanyInfoScreen())),
+                    icon: const Icon(Icons.chevron_right),
+                    label: const Text("詳細"),
+                    style: ElevatedButton.styleFrom(
+                      backgroundColor: Colors.indigo,
+                      foregroundColor: Colors.white,
+                      padding: const EdgeInsets.symmetric(horizontal: 14, vertical: 10),
+                    ),
+                  ),
+                ],
+              ),
+            ),
             _section(
               title: '自社情報',
               subtitle: '会社名・住所・登録番号など',