Since this concerns specific technology, you are most likely better off asking these questions on CK editor forums. I'm not saying you can't get the help here, but the more specific the technology, the less likely you are to find help on a general purpose forum.
However, unless they have specific defaults (likely to be documented), my first guess would be that you have CSS selector rules that for some reason applies to the editor.
I've never used CK, but I could recommend TinyMCE. Iirc, it's found at tinymce.moexicode.com, but a web search should definitely find it for you.
