sourcegit/src/Resources/Styles/TabControl.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style TargetType="{x:Type TabControl}">
        <Setter Property="OverridesDefaultStyle" Value="True" />
        <Setter Property="SnapsToDevicePixels" Value="True" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type TabControl}">
                    <Grid KeyboardNavigation.TabNavigation="Local">
                        <Grid.RowDefinitions>
                            <RowDefinition Height="Auto" />
                            <RowDefinition Height="*" />
                        </Grid.RowDefinitions>
                        <TabPanel x:Name="HeaderPanel" Grid.Row="0" IsItemsHost="True" KeyboardNavigation.TabIndex="1" Background="Transparent" />
                        <Border 
                            x:Name="Border" 
                            Grid.Row="1" 
                            Background="Transparent"    
                            KeyboardNavigation.TabNavigation="Local"
                            KeyboardNavigation.DirectionalNavigation="Contained"
                            KeyboardNavigation.TabIndex="2">
                            <ContentPresenter
                                x:Name="PART_SelectedContentHost" 
                                Margin="4"
                                ContentSource="SelectedContent"/>
                        </Border>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

    <Style TargetType="{x:Type TabItem}">
        <Setter Property="SnapsToDevicePixels" Value="True" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type TabItem}">
                    <Border 
                        x:Name="Border"
                        BorderThickness="0,0,0,1" 
                        BorderBrush="Transparent"
                        Opacity=".56">
                        <ContentPresenter
                            VerticalAlignment="Center" 
                            HorizontalAlignment="Center"
                            ContentSource="Header" 
                            Margin="8,4">
                            <ContentPresenter.Resources>
                                <Style TargetType="{x:Type TextBlock}">
                                    <Setter Property="Foreground" Value="{DynamicResource Brush.FG1}"/>
                                    <Setter Property="FontWeight" Value="DemiBold"/>
                                    <Style.Triggers>
                                        <DataTrigger Binding="{Binding RelativeSource={RelativeSource AncestorType={x:Type TabItem}}, Path=IsSelected}" Value="True">
                                            <Setter Property="Foreground" Value="{DynamicResource Brush.Accent1}"/>
                                        </DataTrigger>
                                    </Style.Triggers>
                                </Style>
                            </ContentPresenter.Resources>
                        </ContentPresenter>
                    </Border>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsSelected" Value="True">
                            <Setter TargetName="Border" Property="BorderBrush" Value="{DynamicResource Brush.Accent1}"/>
                            <Setter TargetName="Border" Property="Opacity" Value="1"/>
                        </Trigger>
                        <MultiTrigger>
                            <MultiTrigger.Conditions>
                                <Condition Property="IsSelected" Value="False"/>
                                <Condition Property="IsMouseOver" Value="True"/>
                            </MultiTrigger.Conditions>
                            <Setter TargetName="Border" Property="BorderBrush" Value="{DynamicResource Brush.Accent2}"/>
                            <Setter TargetName="Border" Property="Opacity" Value=".7"/>
                        </MultiTrigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>