Avalonia/Styles.axaml

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
        x:Class="AvaloniaApplication2.MainWindow"
        Title="AvaloniaApplication2">

	<Window.Styles>
		<Style Selector="Button">
			<Setter Property="Background" Value="#007ACC"/>
			<Setter Property="Foreground" Value="White"/>
			<Setter Property="BorderBrush" Value="#005B99"/>
			<Setter Property="BorderThickness" Value="1"/>
			<Setter Property="CornerRadius" Value="5"/>
			<Setter Property="Padding" Value="10,5"/>
			<Setter Property="FontSize" Value="16"/>
			<Setter Property="FontWeight" Value="Bold"/>
			<Setter Property="Margin" Value="5"/>
			<Setter Property="HorizontalAlignment" Value="Center"/>
			<Setter Property="VerticalAlignment" Value="Center"/>
		</Style>
		<Style Selector="TextBlock">
			<Setter Property="FontSize" Value="16"/>
			<Setter Property="Foreground" Value="#333"/>
			<Setter Property="Margin" Value="5"/>
		</Style>
		<Style Selector="DatePicker">
			<Setter Property="BorderBrush" Value="#007ACC"/>
			<Setter Property="BorderThickness" Value="1"/>
			<Setter Property="CornerRadius" Value="5"/>
			<Setter Property="Padding" Value="5"/>
			<Setter Property="FontSize" Value="16"/>
		</Style>
		<Style Selector="RadioButton">
			<Setter Property="Foreground" Value="#333"/>
			<Setter Property="FontSize" Value="16"/>
			<Setter Property="Margin" Value="5"/>
		</Style>
		<Style Selector="Image">
			<Setter Property="Width" Value="200"/>
			<Setter Property="Height" Value="200"/>
			<Setter Property="Margin" Value="10"/>
			<Setter Property="HorizontalAlignment" Value="Center"/>
			<Setter Property="VerticalAlignment" Value="Center"/>
		</Style>
		<Style Selector="StackPanel">
			<Setter Property="Margin" Value="10"/>
			<Setter Property="HorizontalAlignment" Value="Center"/>
			<Setter Property="VerticalAlignment" Value="Center"/>
		</Style>
	</Window.Styles>
</Window>