That screenshot shows that you have some huge content in the pane, as there are scrollbars and so you should use them to get to the content.
In your css you might be setting big padding or margin for some element, and that's the problem that you are facing. If you can't easily find it out, then check with some tool like Firebug.
Re: ckeditor doesnt show size, format, style
In your css you might be setting big padding or margin for some element, and that's the problem that you are facing. If you can't easily find it out, then check with some tool like Firebug.