Interface.xaml

<DataTemplate x:Key="PeopleGroupHeaderTemplate">
    <Border Background="Transparent" Padding="5">
        <Border Background="{StaticResource PhoneAccentBrush}"
                BorderBrush="{StaticResource PhoneAccentBrush}" BorderThickness="2"
                Width="62"
                Height="62" Margin="0,0,18,0" HorizontalAlignment="Left">
                <TextBlock Text="{Binding Key}" Foreground="{StaticResourcePhoneForegroundBrush}" FontSize="48" Padding="6"
                            FontFamily="{StaticResource PhoneFontFamilySemiLight}"
                            HorizontalAlignment="Left" VerticalAlignment="Center"/>
        </Border>
    </Border>
</DataTemplate>