sourcegit/src/Resources/Styles/CheckBox.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <Style TargetType="{x:Type CheckBox}">
        <Setter Property="Foreground" Value="{DynamicResource Brush.FG1}"/>
        <Setter Property="VerticalAlignment" Value="Center"/>
        <Setter Property="SnapsToDevicePixels" Value="True"/>

        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type CheckBox}">
                    <Grid>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="Auto"/>
                            <ColumnDefinition Width="*"/>
                        </Grid.ColumnDefinitions>

                        <Border x:Name="Border" Grid.Column="0" Width="16" Height="16" VerticalAlignment="Center" BorderBrush="{DynamicResource Brush.Border1}" BorderThickness="1" Background="Transparent">
                            <Path x:Name="Checked" Height="12" Width="12" Style="{DynamicResource Style.Icon}" Data="{DynamicResource Icon.Check}" Fill="{DynamicResource Brush.Accent1}"/>
                        </Border>

                        <ContentPresenter Grid.Column="1" VerticalAlignment="Center" Margin="8,0,0,0" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                    </Grid>

                    <ControlTemplate.Triggers>
                        <Trigger Property="IsChecked" Value="False">
                            <Setter TargetName="Checked" Property="Visibility" Value="Hidden"/>
                        </Trigger>

                        <Trigger Property="IsMouseOver" Value="True">
                            <Setter TargetName="Border" Property="BorderBrush" Value="{DynamicResource Brush.Accent1}"/>
                        </Trigger>

                        <Trigger Property="IsEnabled" Value="False">
                            <Setter Property="Opacity" Value=".5"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>