Yep, that's something you can experience with any of your new templates, especially the ones with colored/dark background. Why this happening? And more important, how you can fix it?
The answer to the first question is simple: the 'WYSIWYG' editors used in Joomla are just doing what the name implies: are taking the template's CSS file and rendering the newly entered content to be as close to what will be shown on the site as possible. And if your template's background is colored or an image file is used to fill your background, then that will be used there too. The fix is relatively easy in the case of most current editors. Almost all of them have the possibility to use a special CSS file in the editing pages. Here we will show you the recipe that works for the family of editors based on TinyMCE editor, delivered by default with Joomla (as JCE), but the solution is similar or can be easily adapted for all such advanced editors.