Avalonia/src/Avalonia.Themes.Default/RepeatButton.xaml

<Styles xmlns="https://github.com/avaloniaui">
    <Style Selector="RepeatButton">
        <Setter Property="Background"
                Value="{DynamicResource ThemeControlMidBrush}" />
        <Setter Property="BorderBrush"
                Value="{DynamicResource ThemeBorderLowBrush}" />
        <Setter Property="BorderThickness"
                Value="{DynamicResource ThemeBorderThickness}" />
        <Setter Property="Foreground"
                Value="{DynamicResource ThemeForegroundBrush}" />
        <Setter Property="HorizontalContentAlignment"
                Value="Center" />
        <Setter Property="VerticalContentAlignment"
                Value="Center" />
        <Setter Property="Padding"
                Value="4" />
        <Setter Property="Template">
            <ControlTemplate>
                <ContentPresenter Name="PART_ContentPresenter"
                                  Background="{TemplateBinding Background}"
                                  BorderBrush="{TemplateBinding BorderBrush}"
                                  BorderThickness="{TemplateBinding BorderThickness}"
                                  ContentTemplate="{TemplateBinding ContentTemplate}"
                                  Content="{TemplateBinding Content}"
                                  Padding="{TemplateBinding Padding}"
                                  TextBlock.Foreground="{TemplateBinding Foreground}"
                                  HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
                                  VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"/>
            </ControlTemplate>
        </Setter>
    </Style>
    <Style Selector="RepeatButton:pointerover /template/ ContentPresenter">
        <Setter Property="BorderBrush"
                Value="{DynamicResource ThemeBorderMidBrush}" />
    </Style>
    <Style Selector="RepeatButton:pressed  /template/ ContentPresenter">
        <Setter Property="Background"
                Value="{DynamicResource ThemeControlHighBrush}" />
    </Style>
    <Style Selector="RepeatButton:disabled">
        <Setter Property="Opacity"
                Value="{DynamicResource ThemeDisabledOpacity}" />
    </Style>
</Styles>