Are there any style properties we should avoid using in a stylesheet assigned to the EditorWysiwygModeCss property?

 

I'm asking because it seems a style added to the stylesheet we were using for this property has cause the textarea of the editor to stop working. We have quite a few styles in this sheet, so I am unsure which one is causing the issue.

 

The symptoms are that typing in the textarea causes a huge text prompt to appear along side the HTML window in the top left, with 100% height. when you type this giant prompt moves (but no giant letters). When I set AutoParseClasses = false, this issue goes away.

 

So I guess the question is what should I look for in my CSS that might be causing the editor to freak out like this?