Shaker/Avalonia/SukiUI/Theme/Calendar/CalendarItem.axaml

<ResourceDictionary xmlns="https://github.com/avaloniaui"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:content="clr-namespace:SukiUI.Content">

    <ControlTheme x:Key="SukiCalendarItemStyle" TargetType="CalendarItem">
        <Setter Property="HorizontalAlignment" Value="Stretch" />
        <Setter Property="VerticalAlignment" Value="Stretch" />
        <Setter Property="DayTitleTemplate">
            <Template>
                <TextBlock HorizontalAlignment="Stretch"
                           VerticalAlignment="Stretch"
                           FontSize="12"
                           Text="{Binding}"
                           TextAlignment="Center" />
            </Template>
        </Setter>
        <Setter Property="Template">
            <ControlTemplate>
                <Border Background="{TemplateBinding Background}"
                        BorderBrush="{TemplateBinding BorderBrush}"
                        BorderThickness="{TemplateBinding BorderThickness}"
                        CornerRadius="{DynamicResource ControlCornerRadius}">
                    <Grid MinWidth="225"
                          HorizontalAlignment="Stretch"
                          VerticalAlignment="Stretch"
                          RowDefinitions="Auto, *">
                        <Grid Name="CalendarHeader"
                              Margin="0,5"
                              ColumnDefinitions="Auto, *, Auto, Auto">
                            <Button Name="PART_HeaderButton"
                                    Grid.Column="0"
                                    Classes="Basic"
                                    FontWeight="{DynamicResource DefaultDemiBold}"
                                    IsEnabled="False" />

                            <Button Name="PART_PreviousButton"
                                    Grid.Column="2"
                                    Classes="NavButton Basic">
                                <PathIcon Classes="Primary Flippable" Data="{x:Static content:Icons.ChevronLeft}" />
                            </Button>

                            <Button Name="PART_NextButton"
                                    Grid.Column="3"
                                    Classes="NavButton Basic">
                                <PathIcon Classes="Primary Flippable" Data="{x:Static content:Icons.ChevronRight}" />
                            </Button>
                        </Grid>

                        <Grid Name="PART_MonthView"
                              Grid.Row="1"
                              Classes="CalendarView"
                              ColumnDefinitions="32,32,32,32,32,32,32"
                              RowDefinitions="32,32,32,32,32,32,32" />

                        <Grid Name="PART_YearView"
                              Grid.Row="1"
                              Classes="CalendarView"
                              ColumnDefinitions="*,*,*,*"
                              RowDefinitions="*,*,*" />
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter>

        <Style Selector="^ /template/ Button.NavButton">
            <Setter Property="Padding" Value="0" />
            <Setter Property="Margin" Value="0,0,18,0" />
            <Style Selector="^ &gt; PathIcon">
                <Setter Property="Width" Value="12" />
                <Setter Property="Height" Value="12" />
            </Style>
        </Style>

        <Style Selector="^ /template/ Button.HeaderButton">
            <Setter Property="Height" Value="24" />
            <Setter Property="TextElement.FontWeight" Value="{DynamicResource DefaultDemiBold}" />
            <Setter Property="Padding" Value="8, 0" />
            <Setter Property="HorizontalContentAlignment" Value="Left" />
        </Style>

        <Style Selector="^ /template/ Grid.CalendarView">
            <Setter Property="IsVisible" Value="False" />
            <Setter Property="MinWidth" Value="240" />
            <Setter Property="HorizontalAlignment" Value="Center" />
            <Setter Property="VerticalAlignment" Value="Center" />
            <Setter Property="MinHeight" Value="225" />
            <Setter Property="Row" Value="1" />
        </Style>
    </ControlTheme>

    <ControlTheme x:Key="{x:Type CalendarItem}"
                  BasedOn="{StaticResource SukiCalendarItemStyle}"
                  TargetType="CalendarItem" />
</ResourceDictionary>