connecting my java project to an external html css files

Hi all
I am trying to display an external html in my web app.I tried using the code below and the page loaded was blank

@Route(value = "test", layout = MainLayout.class)
@PageTitle("test List")
@Tag("bla-bla")
@HtmlImport("src/main/webapp/frontend/src/styles/contact.html")
public class Test extends HorizontalLayout{ 
	public Test() {

	}
}

thanks