ux: chart label style

Signed-off-by: leo <longshuang@msn.cn>

Author: love-linger

src/Views/Chart.cs

@@ -160,6 +160,7 @@ public override void Render(DrawingContext context)
                     {
                         var labelStartX = labelCenterX - formattedLabel.Width * 0.5;
                         var labelStartY = h - formattedLabel.Height - 2.0;
+                        context.DrawLine(new Pen(Brushes.Gray), new Point(labelCenterX, maxSampleH + 4), new Point(labelCenterX, maxSampleH));
                         context.DrawText(formattedLabel, new Point(labelStartX, labelStartY));
                         maxLabelEndX = labelStartX - 16.0;
                     }

src/Views/Statistics.axaml

@@ -202,7 +202,7 @@
                Margin="8,0"
                Samples="{Binding Samples, Mode=OneWay}"
                SampleBrush="{DynamicResource Brush.Accent}"
-               LabelFontFamily="{DynamicResource Fonts.Default}">
+               LabelFontFamily="{DynamicResource Fonts.Monospace}">
         <v:Chart.DataTemplates>
           <DataTemplate DataType="v:ChartToolTip">
             <Border>