Page display using Spring mvc controller appends endpoint to page resources

I have a spring MVC controller that returns a page like this

@Controller
@RequestMapping("/subscriber")
public class SubscriberWebController {
    @GetMapping("/edit/{id}")
    public String getSubscriber(@PathVariable("id") Long id, Model model) {
        model.addAttribute("id", id);
        return "subscriber/manage";
    }

    @GetMapping("/add")
    public String addSubscriber() {
        return "subscriber/manage";
    }
}

The problem is that when manage.html loads, assets are loaded using http://localhost:8081/subscriber/vendor/nucleo/css/nucleo.css rather than http://localhost:8081/vendor/nucleo/css/nucleo.css. This results in a 404 while loading all page resources. I cannot seem to find what I'm doing wrong.

EDIT

I have this configuration in my ApplicationConfiguration so as to help serve all static CSS and JS files.

@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
    registry.addResourceHandler("/**")
            .addResourceLocations("classpath:/static/")
            .setCachePeriod(0);
}

Yet, the issue still persists

You did not say how you reference your CSS inside your manage.html

In case you want your CSS to load from /vendor/nucleo/css/, then put your CSS reference like so:

<link rel="stylesheet" href="vendor/nucleo/css/nucleo.css">

and put a mapping to your vendor package:

<mvc:resources mapping="/vendor/**" location="/ACTUAL LOCATION/"/>

Hope this helps

Taking a cue from @eugen's answer above, I modified my web configuration class thus:

@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
    registry.addResourceHandler("/static/**")
            .addResourceLocations("classpath:/static/")
            .setCachePeriod(0);
}

and in my HTML pages, I reference static resources thus:

<link rel="stylesheet" href="/vendor/nucleo/css/nucleo.css">

Notice the "/" before vendor in the href attribute above. This resolves my issue