diff --git a/DbFirst.BlazorWebApp/Components/CatalogsGrid.razor b/DbFirst.BlazorWebApp/Components/CatalogsGrid.razor
index c425798..5324e66 100644
--- a/DbFirst.BlazorWebApp/Components/CatalogsGrid.razor
+++ b/DbFirst.BlazorWebApp/Components/CatalogsGrid.razor
@@ -25,33 +25,42 @@ else if (items.Count == 0)
 else
 {
     <div class="band-editor">
-        <div class="band-controls">
-            <DxButton Text="Band hinzufügen" Click="AddBand" />
-            <DxButton Text="Layout speichern" Click="SaveLayoutAsync" Enabled="@CanSaveBandLayout" />
-            <DxButton Text="Layout zurücksetzen" Click="ResetLayoutAsync" />
-        </div>
-        @foreach (var band in bandLayout.Bands)
+        <button class="band-editor-toggle" @onclick="() => bandEditorExpanded = !bandEditorExpanded">
+            <span class="band-editor-toggle-icon @(bandEditorExpanded ? "expanded" : "")">&#9658;</span>
+            <span>Band-Layout konfigurieren</span>
+        </button>
+        @if (bandEditorExpanded)
         {
-            <div class="band-row">
-                <DxTextBox Text="@band.Caption" TextChanged="@(value => UpdateBandCaption(band, value))" />
-                <DxButton Text="Entfernen" Click="@(() => RemoveBand(band))" />
+            <div class="band-editor-body">
+                <div class="band-controls">
+                    <DxButton Text="Band hinzufügen" Click="AddBand" />
+                    <DxButton Text="Layout speichern" Click="SaveLayoutAsync" Enabled="@CanSaveBandLayout" />
+                    <DxButton Text="Layout zurücksetzen" Click="ResetLayoutAsync" />
+                </div>
+                @foreach (var band in bandLayout.Bands)
+                {
+                    <div class="band-row">
+                        <DxTextBox Text="@band.Caption" TextChanged="@(value => UpdateBandCaption(band, value))" />
+                        <DxButton Text="Entfernen" Click="@(() => RemoveBand(band))" />
+                    </div>
+                }
+                <DxFormLayout CssClass="band-columns" ColCount="2">
+                    @foreach (var column in columnDefinitions)
+                    {
+                        <DxFormLayoutItem Caption="@column.Caption">
+                            <DxComboBox Data="@bandOptions"
+                                        TData="BandOption"
+                                        TValue="string"
+                                        TextFieldName="Caption"
+                                        ValueFieldName="Id"
+                                        Value="@GetColumnBand(column.FieldName)"
+                                        ValueChanged="@(value => UpdateColumnBand(column.FieldName, value))"
+                                        Width="100%" />
+                        </DxFormLayoutItem>
+                    }
+                </DxFormLayout>
             </div>
         }
-        <DxFormLayout CssClass="band-columns" ColCount="2">
-            @foreach (var column in columnDefinitions)
-            {
-                <DxFormLayoutItem Caption="@column.Caption">
-                    <DxComboBox Data="@bandOptions"
-                                TData="BandOption"
-                                TValue="string"
-                                TextFieldName="Caption"
-                                ValueFieldName="Id"
-                                Value="@GetColumnBand(column.FieldName)"
-                                ValueChanged="@(value => UpdateColumnBand(column.FieldName, value))"
-                                Width="100%" />
-                </DxFormLayoutItem>
-            }
-        </DxFormLayout>
     </div>
 
     <div class="grid-section">
@@ -150,6 +159,7 @@ else
     private List<BandOption> bandOptions = new();
     private Dictionary<string, ColumnDefinition> columnLookup = new();
     private bool gridLayoutApplied;
+    private bool bandEditorExpanded;
 
     private List<ColumnDefinition> columnDefinitions = new()
     {
diff --git a/DbFirst.BlazorWebApp/Components/MassDataGrid.razor b/DbFirst.BlazorWebApp/Components/MassDataGrid.razor
index acbccae..db7eb27 100644
--- a/DbFirst.BlazorWebApp/Components/MassDataGrid.razor
+++ b/DbFirst.BlazorWebApp/Components/MassDataGrid.razor
@@ -37,33 +37,42 @@ else
     </div>
 
     <div class="band-editor">
-        <div class="band-controls">
-            <DxButton Text="Band hinzufügen" Click="AddBand" />
-            <DxButton Text="Layout speichern" Click="SaveLayoutAsync" Enabled="@CanSaveBandLayout" />
-            <DxButton Text="Layout zurücksetzen" Click="ResetLayoutAsync" />
-        </div>
-        @foreach (var band in bandLayout.Bands)
+        <button class="band-editor-toggle" @onclick="() => bandEditorExpanded = !bandEditorExpanded">
+            <span class="band-editor-toggle-icon @(bandEditorExpanded ? "expanded" : "")">&#9658;</span>
+            <span>Band-Layout konfigurieren</span>
+        </button>
+        @if (bandEditorExpanded)
         {
-            <div class="band-row">
-                <DxTextBox Text="@band.Caption" TextChanged="@(value => UpdateBandCaption(band, value))" />
-                <DxButton Text="Entfernen" Click="@(() => RemoveBand(band))" />
+            <div class="band-editor-body">
+                <div class="band-controls">
+                    <DxButton Text="Band hinzufügen" Click="AddBand" />
+                    <DxButton Text="Layout speichern" Click="SaveLayoutAsync" Enabled="@CanSaveBandLayout" />
+                    <DxButton Text="Layout zurücksetzen" Click="ResetLayoutAsync" />
+                </div>
+                @foreach (var band in bandLayout.Bands)
+                {
+                    <div class="band-row">
+                        <DxTextBox Text="@band.Caption" TextChanged="@(value => UpdateBandCaption(band, value))" />
+                        <DxButton Text="Entfernen" Click="@(() => RemoveBand(band))" />
+                    </div>
+                }
+                <DxFormLayout CssClass="band-columns" ColCount="2">
+                    @foreach (var column in columnDefinitions)
+                    {
+                        <DxFormLayoutItem Caption="@column.Caption">
+                            <DxComboBox Data="@bandOptions"
+                                        TData="BandOption"
+                                        TValue="string"
+                                        TextFieldName="Caption"
+                                        ValueFieldName="Id"
+                                        Value="@GetColumnBand(column.FieldName)"
+                                        ValueChanged="@(value => UpdateColumnBand(column.FieldName, value))"
+                                        Width="100%" />
+                        </DxFormLayoutItem>
+                    }
+                </DxFormLayout>
             </div>
         }
-        <DxFormLayout CssClass="band-columns" ColCount="2">
-            @foreach (var column in columnDefinitions)
-            {
-                <DxFormLayoutItem Caption="@column.Caption">
-                    <DxComboBox Data="@bandOptions"
-                                TData="BandOption"
-                                TValue="string"
-                                TextFieldName="Caption"
-                                ValueFieldName="Id"
-                                Value="@GetColumnBand(column.FieldName)"
-                                ValueChanged="@(value => UpdateColumnBand(column.FieldName, value))"
-                                Width="100%" />
-                </DxFormLayoutItem>
-            }
-        </DxFormLayout>
     </div>
 
     <div class="grid-section">
@@ -178,6 +187,7 @@ else
     private List<BandOption> bandOptions = new();
     private Dictionary<string, ColumnDefinition> columnLookup = new();
     private bool gridLayoutApplied;
+    private bool bandEditorExpanded;
 
     private List<ColumnDefinition> columnDefinitions = new()
     {
@@ -281,7 +291,6 @@ else
     {
         if (string.IsNullOrWhiteSpace(layoutUser))
             return;
-
         try
         {
             CaptureColumnLayoutFromGrid();
@@ -299,41 +308,31 @@ else
     {
         if (string.IsNullOrWhiteSpace(layoutUser))
             return;
-
         await BandLayoutService.ResetBandLayoutAsync(LayoutType, LayoutKey, layoutUser);
-
         bandLayout = new BandLayout();
         columnBandAssignments.Clear();
         UpdateBandOptions();
-
         foreach (var column in columnDefinitions)
             column.Width = null;
         columnLookup = columnDefinitions.ToDictionary(c => c.FieldName, StringComparer.OrdinalIgnoreCase);
-
         _sizeMode = SizeMode.Medium;
-
         if (gridRef != null)
             gridRef.LoadLayout(new GridPersistentLayout());
         gridLayoutApplied = false;
-
         infoMessage = "Layout zurückgesetzt.";
         errorMessage = null;
     }
 
     private void CaptureColumnLayoutFromGrid()
     {
-        if (gridRef == null)
-            return;
-
+        if (gridRef == null) return;
         var layout = gridRef.SaveLayout();
         bandLayout.GridLayout = layout;
         bandLayout.SizeMode = _sizeMode;
-
         var orderedColumns = layout.Columns
             .Where(c => !string.IsNullOrWhiteSpace(c.FieldName))
             .OrderBy(c => c.VisibleIndex)
             .ToList();
-
         bandLayout.ColumnOrder = orderedColumns.Select(c => c.FieldName).ToList();
         bandLayout.ColumnWidths = orderedColumns
             .Where(c => !string.IsNullOrWhiteSpace(c.Width))
@@ -407,15 +406,12 @@ else
         builder.OpenComponent<DxGridCommandColumn>(seq++);
         builder.AddAttribute(seq++, "Width", "120px");
         builder.CloseComponent();
-
         var grouped = bandLayout.Bands.SelectMany(b => b.Columns).ToHashSet(StringComparer.OrdinalIgnoreCase);
         foreach (var column in columnDefinitions.Where(c => !grouped.Contains(c.FieldName)))
             BuildDataColumn(builder, ref seq, column);
-
         foreach (var band in bandLayout.Bands)
         {
             if (band.Columns.Count == 0) continue;
-
             builder.OpenComponent<DxGridBandColumn>(seq++);
             builder.AddAttribute(seq++, "Caption", band.Caption);
             builder.AddAttribute(seq++, "Columns", (RenderFragment)(bandBuilder =>
@@ -458,14 +454,12 @@ else
     private void OnEditFieldChanged(object? sender, FieldChangedEventArgs e)
     {
         if (validationMessageStore == null || editContext == null) return;
-
         if (e.FieldIdentifier.FieldName == nameof(MassDataEditModel.UpdateProcedure))
         {
             validationMessageStore.Clear();
             editContext.NotifyValidationStateChanged();
             return;
         }
-
         if (e.FieldIdentifier.FieldName == nameof(MassDataEditModel.CustomerName))
         {
             validationMessageStore.Clear(new FieldIdentifier(editContext.Model, nameof(MassDataEditModel.CustomerName)));
@@ -483,7 +477,6 @@ else
             SetPopupHeaderText(true);
             return;
         }
-
         var item = (MassDataReadDto)e.DataItem;
         e.EditModel = new MassDataEditModel
         {
@@ -505,7 +498,6 @@ else
         infoMessage = null;
         validationMessageStore?.Clear();
         editContext?.NotifyValidationStateChanged();
-
         var editModel = (MassDataEditModel)e.EditModel;
         if (!decimal.TryParse(editModel.AmountText, out var amount))
         {
@@ -513,7 +505,6 @@ else
             e.Cancel = true;
             return;
         }
-
         if (editModel.IsNew)
         {
             var existing = await Api.GetByCustomerNameAsync(editModel.CustomerName);
@@ -524,7 +515,6 @@ else
                 return;
             }
         }
-
         var dto = new MassDataWriteDto
         {
             CustomerName = editModel.CustomerName,
@@ -532,7 +522,6 @@ else
             Category = editModel.Category,
             StatusFlag = editModel.StatusFlag
         };
-
         try
         {
             var saved = await Api.UpsertAsync(dto);
diff --git a/DbFirst.BlazorWebApp/wwwroot/app.css b/DbFirst.BlazorWebApp/wwwroot/app.css
index 64f78e2..30c9d2d 100644
--- a/DbFirst.BlazorWebApp/wwwroot/app.css
+++ b/DbFirst.BlazorWebApp/wwwroot/app.css
@@ -11,6 +11,7 @@ html, body {
 .app-light {
     --band-editor-bg: #f8f9fa;
     --band-editor-border: #dee2e6;
+    --band-toggle-hover-bg: #e9ecef;
 }
 
 .app-dark {
@@ -18,6 +19,7 @@ html, body {
     color: #f1f1f1;
     --band-editor-bg: #2d2d2d;
     --band-editor-border: #444444;
+    --band-toggle-hover-bg: #3a3a3a;
 }
 
 a, .btn-link {
@@ -74,15 +76,47 @@ h1:focus {
 
 /* Grid Band-Editor */
 .band-editor {
-    display: flex;
-    flex-direction: column;
-    gap: 12px;
-    padding: 12px;
     margin-top: 4px;
     margin-bottom: 16px;
     border: 1px solid var(--band-editor-border);
     border-radius: 4px;
     background-color: var(--band-editor-bg);
+    overflow: hidden;
+}
+
+.band-editor-toggle {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    width: 100%;
+    padding: 8px 12px;
+    background: none;
+    border: none;
+    cursor: pointer;
+    font-size: inherit;
+    color: inherit;
+    text-align: left;
+}
+
+    .band-editor-toggle:hover {
+        background-color: var(--band-toggle-hover-bg);
+    }
+
+.band-editor-toggle-icon {
+    font-size: 0.7rem;
+    transition: transform 0.2s ease;
+    display: inline-block;
+}
+
+    .band-editor-toggle-icon.expanded {
+        transform: rotate(90deg);
+    }
+
+.band-editor-body {
+    display: flex;
+    flex-direction: column;
+    gap: 12px;
+    padding: 0 12px 12px 12px;
 }
 
 .band-controls {