Overriding Pivot header foreground brushes in UWP app (Win 10 RTM SDK)

you can also set each pivot item's header to its own unique color

<Pivot>
    <PivotItem>
        <PivotItem.Header>
            <PivotItemHeader Content="Header 1" Foreground="Magenta"/>
        </PivotItem.Header>
        <Grid>
            <!-- pivot item content here -->
        </Grid>
    </PivotItem>
    <PivotItem>
        <PivotItem.Header>
            <PivotItemHeader Content="Header 2" Foreground="Cyan"/>
        </PivotItem.Header>
        <Grid>
            <!-- pivot item content here -->
        </Grid>
    </PivotItem>
</Pivot>

Interestingly, the Foreground property of the PivotItemStyle controls the foreground color of the content within the PivotItem, not the header of it. And there's no way to modify the color of the header within the style.

You might be able to find the corresponding color resources and modify them to achieve what you want, but here's a more flexible and pure xaml way -

The Pivot control actually has a HeaderTemplate which allows you to fully customise your PivotItem headers. See the following code sample, all the headers should have the Teal color.

<Grid>
    <Pivot Title="Pivot">
        <Pivot.HeaderTemplate>
            <DataTemplate>
                <Grid>
                    <TextBlock Text="{Binding}" Foreground="Teal" />
                </Grid>
            </DataTemplate>
        </Pivot.HeaderTemplate>

        <PivotItem Header="My first header">
            <Grid/>
        </PivotItem>
    </Pivot>
</Grid>

---

Update

So here is a better way.

I used the new Live Visual Tree tool in Visual Studio to help locate the actual header element. It's a control called PivotHeaderItem. So turns out, all the styling is defined within this control.

I then had to go to msdn and grabbed the full style of this control (Blend didn't work).

As you can see within the style, the control has a default Foreground of {ThemeResource SystemControlForegroundBaseMediumBrush} and within the visual states, this Foreground gets changed to {ThemeResource SystemControlHighlightAltBaseHighBrush} when the state goes to Selected. I've changed them to Red and Green to make them more obvious.

<Style TargetType="PivotHeaderItem">
    <Setter Property="FontSize" Value="{ThemeResource PivotHeaderItemFontSize}" />
    <Setter Property="FontFamily" Value="{ThemeResource PivotHeaderItemFontFamily}" />
    <Setter Property="FontWeight" Value="{ThemeResource PivotHeaderItemThemeFontWeight}" />
    <Setter Property="CharacterSpacing" Value="{ThemeResource PivotHeaderItemCharacterSpacing}" />
    <Setter Property="Background" Value="Transparent" />
    <Setter Property="Foreground" Value="Red" /> <!-- original value {ThemeResource SystemControlForegroundBaseMediumBrush} -->
    <Setter Property="Padding" Value="{ThemeResource PivotHeaderItemMargin}" />
    <Setter Property="Height" Value="48" />
    <Setter Property="VerticalContentAlignment" Value="Center" />
    <Setter Property="IsTabStop" Value="False" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="PivotHeaderItem">
                <Grid x:Name="Grid" Background="{TemplateBinding Background}">
                    <Grid.Resources>
                        <Style x:Key="BaseContentPresenterStyle" TargetType="ContentPresenter">
                            <Setter Property="FontFamily" Value="Segoe UI" />
                            <Setter Property="FontWeight" Value="SemiBold" />
                            <Setter Property="FontSize" Value="15" />
                            <Setter Property="TextWrapping" Value="Wrap" />
                            <Setter Property="LineStackingStrategy" Value="MaxHeight" />
                            <Setter Property="TextLineBounds" Value="Full" />
                            <Setter Property="OpticalMarginAlignment" Value="TrimSideBearings" />
                        </Style>
                        <Style x:Key="BodyContentPresenterStyle" TargetType="ContentPresenter" BasedOn="{StaticResource BaseContentPresenterStyle}">
                            <Setter Property="FontFamily" Value="{ThemeResource PivotHeaderItemFontFamily}" />
                            <Setter Property="FontWeight" Value="{ThemeResource PivotHeaderItemThemeFontWeight}" />
                            <Setter Property="FontSize" Value="{ThemeResource PivotHeaderItemFontSize}" />
                        </Style>
                    </Grid.Resources>
                    <VisualStateManager.VisualStateGroups>
                        <VisualStateGroup x:Name="SelectionStates">
                            <VisualStateGroup.Transitions>
                                <VisualTransition From="Unselected" To="UnselectedLocked" GeneratedDuration="0:0:0.33" />
                                <VisualTransition From="UnselectedLocked" To="Unselected" GeneratedDuration="0:0:0.33" />
                            </VisualStateGroup.Transitions>
                            <VisualState x:Name="Disabled">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlDisabledBaseMediumLowBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Unselected" />
                            <VisualState x:Name="UnselectedLocked">
                                <Storyboard>
                                    <DoubleAnimation Storyboard.TargetName="ContentPresenterTranslateTransform" Storyboard.TargetProperty="X" Duration="0" To="{ThemeResource PivotHeaderItemLockedTranslation}" />
                                    <DoubleAnimation Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="(UIElement.Opacity)" Duration="0" To="0" />
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="Selected">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="Green" /> <!-- original value {ThemeResource SystemControlHighlightAltBaseHighBrush} -->
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Grid" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightTransparentBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="UnselectedPointerOver">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltBaseMediumHighBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Grid" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightTransparentBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="SelectedPointerOver">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltBaseMediumHighBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Grid" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightTransparentBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="UnselectedPressed">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltBaseMediumHighBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Grid" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightTransparentBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                            <VisualState x:Name="SelectedPressed">
                                <Storyboard>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="ContentPresenter" Storyboard.TargetProperty="Foreground">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightAltBaseMediumHighBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                    <ObjectAnimationUsingKeyFrames Storyboard.TargetName="Grid" Storyboard.TargetProperty="Background">
                                        <DiscreteObjectKeyFrame KeyTime="0" Value="{ThemeResource SystemControlHighlightTransparentBrush}" />
                                    </ObjectAnimationUsingKeyFrames>
                                </Storyboard>
                            </VisualState>
                        </VisualStateGroup>
                    </VisualStateManager.VisualStateGroups>
                    <ContentPresenter x:Name="ContentPresenter" Content="{TemplateBinding Content}" ContentTemplate="{TemplateBinding ContentTemplate}" Margin="{TemplateBinding Padding}" FontSize="{TemplateBinding FontSize}" FontFamily="{TemplateBinding FontFamily}" FontWeight="{TemplateBinding FontWeight}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}">
                        <ContentPresenter.RenderTransform>
                            <TranslateTransform x:Name="ContentPresenterTranslateTransform" />
                        </ContentPresenter.RenderTransform>
                    </ContentPresenter>
                </Grid>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

With this, you should now be able to fully customise your pivot headers! :)