Vertical Layout Height 0px with scss custom theme

Vaadin 6 / 7 / 8
1

Hello,
I am doing some experiments with 7.0.0 but i am having an unexpected behavior when using scss setted theme. Without it behaves as expected but with the custom theme, the vertical layouts become 0px heigth

Without : @Theme(“main-theme”) is all OK, but with the annotation and scss files set, only the witdh is set

@SuppressWarnings("serial")
@Theme("main-theme")
public class MyVaadinUI extends UI
{

    @Override
    protected void init(VaadinRequest request) {
        VerticalLayout mainLayout = new VerticalLayout();
        mainLayout.setSizeFull();
        setContent(mainLayout);

        VerticalLayout northLayout = new VerticalLayout();
        northLayout.setSizeFull();
        northLayout.addStyleName("northLayout");
        mainLayout.addComponent(northLayout);

        VerticalLayout southLayout = new VerticalLayout();
        southLayout.setSizeFull();
        southLayout.addStyleName("southLayout");
        mainLayout.addComponent(southLayout);


        mainLayout.setExpandRatio(northLayout,	0.33f);
        mainLayout.setExpandRatio(southLayout, 0.66f);
    }


}

main-theme.scss:


@import "../reindeer/reindeer.scss";

@mixin main-theme {

  @include reindeer;

}

styles.scss:


@import "main-theme.scss";

.main-theme {
  @include main-theme;
}

Can you help me check if this i am missing any configuration or is a layout issue?

Thank you