How to add a closebox to my Panel

Hello,

I want to add a close button to my Panel component and I need that button to look and feel like a Vaadin window closebox. At the moment I've got:

private final Label closeBox = new Label();
closeBox.addStyleName("v-window-closebox");

and it works!

But.. first of all I'm not sure if using a Label for that purpose is a good idea. But what's more important, I'm getting a black-styled button which is no good for my application. How can I change it to be like in WINDOW_LIGHT style? I wast trying with

closeBox.addStyleName(Reindeer.WINDOW_LIGHT);

but it doesn't work. Any ideas, please?