A modern dark theme for Swagger UI based on itz-fork/Fastapi.
In Program.cs or Startup.cs:
app.UseSwaggerUI(c => {
c.InjectStylesheet("/swagger-ui/swagger_ui_dark.css");
});
app.UseStaticFiles();
Make a top-level wwwroot/swagger-ui/ directory in your project and add swagger_ui_dark.css to it.