With some themes CKEditor in Drupal does not work right by default, e.g. where the background in the text-field is to dark. For the Marienelli theme, the solution is presented here:

 http://drupal.ckeditor.com/tricks.

But the same problems show up with this theme as well; Absynthe

The added code in the ckeditor.config.js-file regarding the Marienelli theme is: 

config.bodyClass = 'singlepage';

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