<Window
    x:Class="WpfApp1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:local="clr-namespace:WpfApp1"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    Title="MainWindow"
    Width="525"
    Height="350"
    mc:Ignorable="d">
    <Window.Resources>
        <Style x:Key="Style1" TargetType="TextBlock">
            <Setter Property="FontSize" Value="24" />
        </Style>
        <Style
            x:Key="Style2"
            BasedOn="{StaticResource Style1}"
            TargetType="TextBlock">
            <Setter Property="FontWeight" Value="Bold" />
        </Style>
        <Style
            x:Key="Style3"
            BasedOn="{StaticResource Style2}"
            TargetType="TextBlock">
            <Setter Property="Background" Value="Red" />
        </Style>
    </Window.Resources>
    <TextBlock Style="{StaticResource Style3}">This is a test!</TextBlock>
</Window>