<Application
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    x:Class="WorkingWithStyles.App">
    <Application.Resources>
        <ResourceDictionary>
            <Style TargetType="Label">
                <Setter Property="TextColor" Value="Green" />
            </Style>
        </ResourceDictionary>
    </Application.Resources>
</Application>	