Q:

Static files are not found/served to a SPA when files are outside the wwwroot

I created a asp.net core 1.0 website project with multiple areas.
In the application area`s HomeController I have this action:
public IActionResult Index()
{
    string content = System.IO.File.ReadAllText("./Areas/Application/App/Index.html");
    return base.Content(content, new MediaTypeHeaderValue("text/html"));
}

When the html file is returned many 404 errors from not found javascript library files occur in my browser.
The index.html with all its .js files is a SPA inside a asp.net core website area.
This SPA is built + deployed to the websiteproject/areas/application/App folder.
When I build + deploy the SPA to the wwwroot folder then all the static files are found.
I guess this means the static file path is always relative to wwwroot to make the SPA work.
Question 1: Is there any way to configure the wwwroot folder as wwwroot/app path with the WebHostBuilder class via:
 .UseWebRoot("./wwwroot/app")

just and explicitly for the application area?
That means the wwwroot for the website should continue to work?
The best thing I would achieve is a wwwroot folder with 2 subfolders:

website
app

and I would like to configure 2 wwwroot`s path website and app for default 'area' and the explicit application area.
Question 2: How can I do that?
UPDATE 1
According to Pawel comment I changed:
   app.UseStaticFiles();

to:
app.UseStaticFiles();
app.UseStaticFiles(new StaticFileOptions()
{
    FileProvider = new PhysicalFileProvider(Path.Combine(Directory.GetCurrentDirectory(), "Areas","Application", "App")),
    RequestPath = new PathString("/Application")
});

But still I get the same 404 errors for the .js file as if they would not be available in the wwwroot directory ???
404
  In the developer console tools requested by the single page app:
http://localhost:52159/vendor/reflect-metadata/Reflect.js (404)

200
  Entered manually in the browser url bar:
http://localhost:52159/Application/vendor/reflect-metadata/Reflect.js

Does that mean the static file serving in asp.net core works, but there is something else which works not somehow? I guess I should not change something in the SPA that would be stupid...
I added a screenshot of my file structure that you guys better understand my problem or maybe find my user error...:

A:

Now I found a solution where  have to apply the changes.
system.config.ts
System.config({
  map: {
    '@angular': 'Application/vendor/@angular',
    'rxjs': 'Application/vendor/rxjs',
    'main': 'Application/main.js',
    'app': 'Application/app',
  },
  packages: cliSystemConfigPackages
});

That way all angular 2/rxjs files are served from the directory path: 
"Area/Application/App" when the url "/Application" is entered.
Also I had to prepend 'Application' to the main and the root barrel 'app'.
index.html
<body>
  <app-root>Loading...</app-root>

    {{#each scripts.polyfills}}
    <script src="Application/{{.}}"></script>
    {{/each}}
    <script>
      System.import('Application/system-config.js').then(function () {
        System.import('Application/main.js');
      }).catch(console.error.bind(console));
    </script>
</body>
</html>

These are the changes in the index.html file.
Now my Asp.net core Area 'Application' has its own "wwwroot" separated from the wwwroot of the public website.

