How to set Web Page margin to Zero(0) using GWT

[Stephen George]

When i'm adding a button to the page using the following code there is
some margin. i'm using GWT 2.4.0



import com.google.gwt.core.client.

EntryPoint;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.RootPanel;

public class GWTApplication implements EntryPoint {
       public void onModuleLoad() {
               RootPanel.get().add(new Button("Button"));
      }
}


i don't want the margin in the web page.
Please help me.


Thank you.