Wpf resources from referenced library not showing during design time

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XAML

WPF

designer

I must either be dumb or blind. I have created a WPF application. Along with that application, I created a library. In the same solution and the library is referenced in the application project. The library is to be used as a theming library. The styles are shown during runtime of the application. However, during design time, Most styles are shown. However, the style for the Windows are not shown. I am using Visual Studio 2019.

What I have tried:

I have tried adding the DesignTimeResources.xaml file to the Properties directory and set the ItemGroup in the csproj file as was suggested on other sites. The styles still do not show for the Window.