Valo theme and readonly DateField

Hello !
I have found than readonly DateField creates strange visual artifact then using Valo theme (see screenshot) . Other themes, and non-readonly DateFields works fine. Is there any workaround for this issue (css/sass rules, etc ) ?
Test code:

@Theme("valo")
@SuppressWarnings("serial")
public class ValoDateFieldTest extends UI {

    @WebServlet(value = "/*", asyncSupported = true)
    @VaadinServletConfiguration(productionMode = false, ui = ValoDateFieldTest.class, widgetset = VaadinServlet.DEFAULT_WIDGETSET)
    public static class Servlet extends VaadinServlet {
    }

    @Override
    protected void init(VaadinRequest request) {
        setupTheme(request);

        VerticalLayout verticalLayout = new VerticalLayout();
        verticalLayout.setMargin(true);
        DateField dateField = new DateField("Date field", new Date());
        dateField.setReadOnly(true);
        verticalLayout.addComponent(dateField);

        setContent(verticalLayout);
    }

    protected void setupTheme(VaadinRequest request) {
        String theme = request.getParameter("theme");
        if (theme != null && theme.trim().length() > 0)
            setTheme(theme.trim());
    }

}

Sorry. I’m forget to attach screenshot.
16320.png

See
https://vaadin.com/forum#!/thread/8126101/8145190

Thanks.