如何使用VisualState更改TextBlock字体大小?

我有一个页面不想在调整TextBlock大小时设置其字体大小。我使用的是VisualStateManager,但我一定做错了什么。

    <Page
        x:Class="MyUWP.Pages.SplashPage"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="using:StoryFractalUWP.Pages"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d">
        <VisualStateManager.VisualStateGroups>
            <VisualStateGroup>
                <VisualState x:Name="Narrow">
                    <VisualState.StateTriggers>
                        <AdaptiveTrigger MinWindowWidth="0" />
                    </VisualState.StateTriggers>
                    <VisualState.Setters>
                        <Setter Target="MainTitle.FontSize" Value="36" />
                    </VisualState.Setters>
                </VisualState>
                <VisualState x:Name="Normal">
                    <VisualState.StateTriggers>
                        <AdaptiveTrigger MinWindowWidth="600" />
                    </VisualState.StateTriggers>
                    <VisualState.Setters>
                        <Setter Target="MainTitle.FontSize" Value="72" />
                    </VisualState.Setters>
                </VisualState>
                <VisualState x:Name="Wide">
                    <VisualState.StateTriggers>
                        <AdaptiveTrigger MinWindowWidth="1000" />
                    </VisualState.StateTriggers>
                    <VisualState.Setters>
                        <Setter Target="MainTitle.FontSize" Value="110" />
                    </VisualState.Setters>
                </VisualState>
            </VisualStateGroup>
        </VisualStateManager.VisualStateGroups>

        <RelativePanel Background="White" x:Name="MainPanel">
            <TextBlock x:Name="MainTitle" RelativePanel.AlignHorizontalCenterWithPanel="True"
                       RelativePanel.AlignVerticalCenterWithPanel="True"
                       >MyApp</TextBlock>

        </RelativePanel>
    </Page>

我做错了什么?