More info on this. After further investigation, it appears that the css property "
float:right;" is causing the issues. For some reason, if this appears anywhere in your CSS declaration for either the page or the editor, the dropdown for CSS styles will render over 100% in width...very strange. Remove all instances of float:right and everything is fine.
Since I need float:right to render multiple page elements, this is a bug -- at least to me.
Jamie