MyCalanderHome/MyCalendarHome/StyleCalendar.axaml

<Styles xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
  <Design.PreviewWith>
    <Border Padding="20">
      <!-- Add Controls for Previewer Here -->
    </Border>
  </Design.PreviewWith>

  <!-- Add Styles Here -->
	<Style Selector="Button">
		<Setter Property="Background" Value="DarkGreen"/>
		<Setter Property="Foreground" Value="WhiteSmoke"/>
	</Style>
	<Style Selector="TextBlock">
		<Setter Property="FontSize" Value="16"/>
		<Setter Property="Foreground" Value="DarkGreen"/>
		<Setter Property="FontWeight" Value="Bold"/>
	</Style>
	<Style Selector="TextBlock.Error">
		<Setter Property="FontSize" Value="16"/>
		<Setter Property="Foreground" Value="Red"/>
		<Setter Property="FontWeight" Value="Bold"/>
	</Style>
	<Style Selector="Border">
		<Setter Property="Background" Value="White"/>
		<Setter Property="BorderBrush" Value="LightGray"/>
		<Setter Property="BorderThickness" Value="2"/>
		<Setter Property="CornerRadius" Value="16"/>
	</Style>
	<Style Selector="Label">
		<Setter Property="FontSize" Value="16"/>
		<Setter Property="Foreground" Value="DarkGreen"/>
		<Setter Property="FontWeight" Value="Bold"/>
	</Style>

</Styles>