Hide feedback when there are no messages

[Николай Кучумов]

Hello.
I'm currently developing a sign up form using Wicket.
I've stylized the error feedback panel to make it look red, and now i see
this red panel even when there are no messages at all.
Can you advice me something to make the feedback panel div invisible when
there are no messages?
*You can get the idea by going to http://vostrets.ru/register/ - the error
panel is empty but is still visible...