Shaker/OxyPlot/OxyPlot.Avalonia/Themes/Default.axaml

<Styles xmlns="https://github.com/avaloniaui" 
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="http://oxyplot.org/avalonia"
        xmlns:converters="clr-namespace:OxyPlot.Avalonia.Converters">

    <Style Selector="local|TrackerControl">
        <Setter Property="Background" Value="#E0FFFFA0" />
        <Setter Property="BorderBrush" Value="Black" />
        <Setter Property="BorderThickness" Value="1" />
        <Setter Property="LineStroke" Value="#80000000" />
        <Setter Property="HorizontalLineVisibility" Value="true" />
        <Setter Property="VerticalLineVisibility" Value="true" />
        <Setter Property="Distance" Value="7" />
        <Setter Property="CornerRadius" Value="0" />
        <Setter Property="ShowPointer" Value="true" />
        <Setter Property="CanCenterHorizontally" Value="true" />
        <Setter Property="CanCenterVertically" Value="true" />
        <Setter Property="IsHitTestVisible" Value="false" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate>
                    <Canvas HorizontalAlignment="Stretch" VerticalAlignment="Stretch" ClipToBounds="False">
                        <Line Name="PART_HorizontalLine" IsVisible="{TemplateBinding HorizontalLineVisibility}"
                  Stroke="{TemplateBinding LineStroke}"
                  StrokeDashArray="{TemplateBinding LineDashArray}" />
                        <Line Name="PART_VerticalLine" IsVisible="{TemplateBinding VerticalLineVisibility}"
                  Stroke="{TemplateBinding LineStroke}"
                  StrokeDashArray="{TemplateBinding LineDashArray}" />
                        <Panel Name="PART_ContentContainer" ClipToBounds="False">
                            <Path Name="PART_Path" Fill="{TemplateBinding Background}" Stroke="{TemplateBinding BorderBrush}"
                    StrokeThickness="{TemplateBinding BorderThickness, Converter={x:Static converters:ThicknessConverter.Instance}}" />
                            <ContentPresenter Name="PART_Content" Content="{TemplateBinding Content}" HorizontalAlignment="Center" />
                        </Panel>
                    </Canvas>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

    <Style Selector="local|PlotView">
        <Setter Property="Background" Value="White" />
        <Setter Property="DefaultTrackerTemplate">
            <Setter.Value>
                <ControlTemplate>
                    <local:TrackerControl Position="{Binding Position}" LineExtents="{Binding PlotModel.PlotArea}">
                        <local:TrackerControl.Content>
                            <TextBlock Text="{Binding Text}" Margin="7" />
                        </local:TrackerControl.Content>
                    </local:TrackerControl>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Setter Property="ZoomRectangleTemplate">
            <Setter.Value>
                <ControlTemplate>
                    <Rectangle Fill="#40FFFF00" Stroke="Black" StrokeDashArray="3,1" />
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate>
                    <Border Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}"
                  BorderThickness="{TemplateBinding BorderThickness}">
                        <Panel Name="PART_Panel" />
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

    <Style Selector="local|Plot">
        <Setter Property="Background" Value="White" />
        <Setter Property="DefaultTrackerTemplate">
            <Setter.Value>
                <ControlTemplate>
                    <local:TrackerControl Position="{Binding Position}" LineExtents="{Binding PlotModel.PlotArea}">
                        <local:TrackerControl.Content>
                            <TextBlock Text="{Binding Text}" Margin="7" />
                        </local:TrackerControl.Content>
                    </local:TrackerControl>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Setter Property="ZoomRectangleTemplate">
            <Setter.Value>
                <ControlTemplate>
                    <Rectangle Fill="#40FFFF00" Stroke="Black" StrokeDashArray="3,1" />
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate>
                    <Border Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}"
                  BorderThickness="{TemplateBinding BorderThickness}">
                        <Panel Name="PART_Panel" />
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</Styles>