ASP.NET Core MVC Rewrite and Default document

I'm trying to set Core MVC Rewrite so:

• when

  localhost/part

  is requested, it responds with the default

  localhost/part/index.html

• when

  localhost/part/[anything]

  , then still responds with

  index.html

  (

  localhost/part/index.html

  )

Here's what I have now:

app.UseRewriter(new RewriteOptions().AddRewrite("part(\\/.*)?", "part/index.html", true));

app.UseDefaultFiles();
app.UseStaticFiles();
app.UseIdentity();
app.UseMvc(...);

So now, when

localhost/part/[anything]/[something]

is requested, it does serve

index.html

. But it serves it as

localhost/part/[anything]/[something]/index.html

and this is a problem with Angular's BASE_HREF. So app showsLoading... and nothing else is loaded obviously. Hm... This requires a fix from Angular's part. And I have no idea for the fix right now. Anyone?