import com.vaadin.flow.component.button.Button; import com.vaadin.flow.component.orderedlayout.VerticalLayout; import com.vaadin.flow.router.Route; import com.vaadin.flow.theme.Theme; import com.vaadin.flow.theme.lumo.Lumo; @Route("") @Theme(value = Lumo.class, variant = Lumo.LIGHT) public class MainView extends VerticalLayout { public MainView() { Button button = new Button("Click me"); add(button); } }