Shrlalgo.RvKits/WPFluent/Controls/LoadingScreen/LoadingScreen.xaml

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:controls="clr-namespace:WPFluent.Controls"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <Style TargetType="{x:Type controls:LoadingScreen}">
        <Setter Property="Foreground" Value="{DynamicResource TextFillColorPrimaryBrush}" />
        <Setter Property="Background" Value="{DynamicResource ApplicationBackgroundColorBrush}" />
        <Setter Property="SnapsToDevicePixels" Value="True" />
        <Setter Property="OverridesDefaultStyle" Value="True" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type controls:LoadingScreen}">
                    <Grid
                        Background="{TemplateBinding Background}"
                        Height="{TemplateBinding Height}"
                        Width="{TemplateBinding Width}">
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="*" />
                            <ColumnDefinition Width="*" />
                        </Grid.ColumnDefinitions>

                        <Grid Grid.Column="0" VerticalAlignment="Center">
                            <controls:ProgressRing IsIndeterminate="True" />
                        </Grid>

                        <Grid Grid.Column="1" VerticalAlignment="Center">
                            <ContentPresenter />
                        </Grid>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

</ResourceDictionary>