diff --git a/SpineViewer/App.xaml.cs b/SpineViewer/App.xaml.cs
index e3064ac..359deba 100644
--- a/SpineViewer/App.xaml.cs
+++ b/SpineViewer/App.xaml.cs
@@ -331,7 +331,7 @@ namespace SpineViewer
             get => _language;
             set
             {
-                var uri = $"Resources/Strings/{value.ToString().ToLower()}.xaml";
+                var uri = $"Resources/Strings/{value.ToString().ToLowerInvariant()}.xaml";
                 try
                 {
                     Resources.MergedDictionaries.Add(new() { Source = new(uri, UriKind.Relative) });
@@ -351,7 +351,7 @@ namespace SpineViewer
             get => _skin;
             set
             {
-                var uri = $"Resources/Skins/{value.ToString().ToLower()}.xaml";
+                var uri = $"Resources/Skins/{value.ToString().ToLowerInvariant()}.xaml";
                 try
                 {
                     Resources.MergedDictionaries.Add(new() { Source = new(uri, UriKind.Relative) });
diff --git a/SpineViewer/Extensions/WpfExtension.cs b/SpineViewer/Extensions/WpfExtension.cs
index b1aa789..d5cd487 100644
--- a/SpineViewer/Extensions/WpfExtension.cs
+++ b/SpineViewer/Extensions/WpfExtension.cs
@@ -40,7 +40,7 @@ namespace SpineViewer.Extensions
 
         //public static void SaveToFile(this BitmapSource bitmap, string path)
         //{
-        //    var ext = Path.GetExtension(path)?.ToLower();
+        //    var ext = Path.GetExtension(path)?.ToLowerInvariant();
         //    BitmapEncoder encoder = ext switch
         //    {
         //        ".jpg" or ".jpeg" => new JpegBitmapEncoder(),
diff --git a/SpineViewer/ViewModels/Exporters/CustomFFmpegExporterViewModel.cs b/SpineViewer/ViewModels/Exporters/CustomFFmpegExporterViewModel.cs
index 7dcc382..f1afde6 100644
--- a/SpineViewer/ViewModels/Exporters/CustomFFmpegExporterViewModel.cs
+++ b/SpineViewer/ViewModels/Exporters/CustomFFmpegExporterViewModel.cs
@@ -36,7 +36,7 @@ namespace SpineViewer.ViewModels.Exporters
         public string? CustomArgs { get => _customArgs; set => SetProperty(ref _customArgs, value); }
         protected string? _customArgs;
 
-        private string FormatSuffix => $".{_format.ToString().ToLower()}";
+        private string FormatSuffix => $".{_format.ToString().ToLowerInvariant()}";
 
         public override string? Validate()
         {
diff --git a/SpineViewer/ViewModels/Exporters/FFmpegVideoExporterViewModel.cs b/SpineViewer/ViewModels/Exporters/FFmpegVideoExporterViewModel.cs
index fb2f532..474c03b 100644
--- a/SpineViewer/ViewModels/Exporters/FFmpegVideoExporterViewModel.cs
+++ b/SpineViewer/ViewModels/Exporters/FFmpegVideoExporterViewModel.cs
@@ -77,7 +77,7 @@ namespace SpineViewer.ViewModels.Exporters
         public bool EnableParamProfile =>
             _format == FFmpegVideoExporter.VideoFormat.Mov;
 
-        private string FormatSuffix => $".{_format.ToString().ToLower()}";
+        private string FormatSuffix => $".{_format.ToString().ToLowerInvariant()}";
 
         protected override void Export(SpineObjectModel[] models)
         {
diff --git a/SpineViewer/ViewModels/Exporters/FrameExporterViewModel.cs b/SpineViewer/ViewModels/Exporters/FrameExporterViewModel.cs
index a30363a..5a27099 100644
--- a/SpineViewer/ViewModels/Exporters/FrameExporterViewModel.cs
+++ b/SpineViewer/ViewModels/Exporters/FrameExporterViewModel.cs
@@ -34,7 +34,7 @@ namespace SpineViewer.ViewModels.Exporters
             {
                 if (_format == SKEncodedImageFormat.Heif) return ".jpeg";
                 else if (_format == SKEncodedImageFormat.Jpegxl) return ".jpeg";
-                else return $".{_format.ToString().ToLower()}";
+                else return $".{_format.ToString().ToLowerInvariant()}";
             }
         }
 
diff --git a/SpineViewer/ViewModels/MainWindow/ExplorerListViewModel.cs b/SpineViewer/ViewModels/MainWindow/ExplorerListViewModel.cs
index 0f85b90..3a56496 100644
--- a/SpineViewer/ViewModels/MainWindow/ExplorerListViewModel.cs
+++ b/SpineViewer/ViewModels/MainWindow/ExplorerListViewModel.cs
@@ -333,7 +333,7 @@ namespace SpineViewer.ViewModels.MainWindow
                 {
                     foreach (var file in Directory.EnumerateFiles(_currentDirectory, "*.*", SearchOption.AllDirectories))
                     {
-                        var lowerPath = file.ToLower();
+                        var lowerPath = file.ToLowerInvariant();
                         if (SpineObject.PossibleSuffixMapping.Keys.Any(lowerPath.EndsWith))
                             _items.Add(new(file));
                     }
diff --git a/SpineViewer/ViewModels/MainWindow/SpineObjectListViewModel.cs b/SpineViewer/ViewModels/MainWindow/SpineObjectListViewModel.cs
index 0615ac4..c60d7e6 100644
--- a/SpineViewer/ViewModels/MainWindow/SpineObjectListViewModel.cs
+++ b/SpineViewer/ViewModels/MainWindow/SpineObjectListViewModel.cs
@@ -450,7 +450,7 @@ namespace SpineViewer.ViewModels.MainWindow
             {
                 if (File.Exists(path))
                 {
-                    var lowerPath = path.ToLower();
+                    var lowerPath = path.ToLowerInvariant();
                     if (SpineObject.PossibleSuffixMapping.Keys.Any(lowerPath.EndsWith))
                         validPaths.Add(path);
                 }
@@ -458,7 +458,7 @@ namespace SpineViewer.ViewModels.MainWindow
                 {
                     foreach (var file in Directory.EnumerateFiles(path, "*.*", SearchOption.AllDirectories))
                     {
-                        var lowerPath = file.ToLower();
+                        var lowerPath = file.ToLowerInvariant();
                         if (SpineObject.PossibleSuffixMapping.Keys.Any(lowerPath.EndsWith))
                             validPaths.Add(file);
                     }
diff --git a/SpineViewer/Views/MainWindow.xaml b/SpineViewer/Views/MainWindow.xaml
index 2949858..1a16917 100644
--- a/SpineViewer/Views/MainWindow.xaml
+++ b/SpineViewer/Views/MainWindow.xaml
@@ -73,7 +73,7 @@
             <Border Grid.Row="1">
                 <Grid x:Name="_rootGrid">
                     <Grid.ColumnDefinitions>
-                        <ColumnDefinition/>
+                        <ColumnDefinition Width="*"/>
                         <ColumnDefinition Width="Auto"/>
                         <ColumnDefinition Width="2.5*"/>
                     </Grid.ColumnDefinitions>