<Window x:Class="WpfApp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="WPF单选按钮背景颜色" Height="450" Width="800">
    <Grid>
        <StackPanel>
            <RadioButton Content="选项1" Style="{StaticResource CustomRadioButtonStyle}" />
            <RadioButton Content="选项2" Style="{StaticResource CustomRadioButtonStyle}" />
            <RadioButton Content="选项3" Style="{StaticResource CustomRadioButtonStyle}" />
        </StackPanel>
    </Grid>
</Window>

<Window.Resources>
    <Style x:Key="CustomRadioButtonStyle" TargetType="RadioButton">
        <Setter Property="Background" Value="LightBlue" />
        <Setter Property="Foreground" Value="White" />
        <Setter Property="FontSize" Value="16" />
        <!-- 其他样式设置 -->
    </Style>
</Window.Resources>