Angular Project Styles and Images Not Deployed in Spring Project

I deployed my Angular (4) Project in the Spring MVC Project. Everything works except the External Stylesheets and the Images files. I included the external Stylesheets in the style.css file of the Angular Project like this

@import url("/assets/css/header.css");
@import url("/assets/css/footer.css");
@import url("/assets/css/content.css");

and the I used the Image files in some styles like this:

.check-status{
    background-image: url("/assets/images/header.png");
}

I am getting Error Messages like this:

GET http://localhost:8080/assets/css/footer.css net::ERR_ABORTED GET http://localhost:8080/assets/images/header 404 ()

Is it related to the Angular Project Build Problem? If yes, How do I need to build the Angular Project so that I can deploy in the Spring MVC Project?