Swagger and .Net COre cannot find custom.css - asp.net-core

Question

I've built an API project with .Net Core 3.0, adding Swagger 5.rc4 to show API documentation.
I want to customize CSS so I've added in the startup.Configure:
app.UseSwaggerUI(c =>
{
c.SwaggerEndpoint("/swagger/v1/swagger.json", "Geo API");
c.RoutePrefix = "docs";
c.DocumentTitle = "GeoData APIs";
c.DisplayRequestDuration();
c.EnableFilter();
c.InjectStylesheet("/swagger-ui/custom.css");
});
I can see the swagger page at localhost:8888/docs/index.html but I'm not able to make it load the custom.css
In my project, I've created a folder "swagger-ui" containing the file custom.css, and set to be copied to the output directory. I can correctly see it, inside the swagger-ui folder, in the bin folder when I compile but no way to see it from the browser.
I've added also app.UseStaticFiles(); but nothing has changed.

Answer 1

You could try steps below:
Create Asp.NET Core Web API 3.0
Edit the csproj to add reference below:
<PackageReference Include="Swashbuckle.AspNetCore" Version="5.0.0-rc4" />
Add swagger-ui and custom.css to wwwroot with content below:
body {
background-color:yellow
}
Change Startup.cs
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
services.AddControllersWithViews().AddNewtonsoftJson();
services.AddSwaggerGen(c =>
{
c.SwaggerDoc("v1", new OpenApiInfo { Title = "My API", Version = "v1" });
});
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
{
app.UseExceptionHandler("/Home/Error");
// The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
app.UseHsts();
}
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.UseSwagger();
app.UseSwaggerUI(c =>
{
c.SwaggerEndpoint("/swagger/v1/swagger.json", "Geo API");
c.RoutePrefix = "docs";
c.DocumentTitle = "GeoData APIs";
c.DisplayRequestDuration();
c.EnableFilter();
c.InjectStylesheet("/swagger-ui/custom.css");
});
app.UseEndpoints(endpoints =>
{
endpoints.MapControllerRoute(
name: "default",
pattern: "{controller=Home}/{action=Index}/{id?}");
});
}
}