How to style the Scheduler header in WinUI (Calendar)
Customize the header appearance of the scheduler by using the SchedulerHeaderControl in the WinUI Scheduler. Change the background color, FontStyle, and BorderBrush, etc. by targeting the style for the SchedulerHeaderControl.
XAML
Customize the header appearance of the scheduler by setting the style property for the SchedulerHeaderControl.
<Grid> <Grid.Resources> <Style TargetType="scheduler:SchedulerHeaderControl"> <Setter Property="Background" Value="LightCyan"/> <Setter Property="Foreground" Value="Red"/> <Setter Property="FontStyle" Value="Italic"/> <Setter Property="BorderBrush" Value="LightCoral"/> <Setter Property="BorderThickness" Value="2"/> </Style> </Grid.Resources> <scheduler:SfScheduler x:Name="Schedule" ViewType="Month"> </scheduler:SfScheduler> </Grid>

Take a moment to pursue the documentation. You can also find the options for header appearance customization.