I recently uploaded my own dark-theme called "IVYSAUR" to github, check it out here.
It tells you how to install it, and although it may not be exactly what you're looking for, if you download the widget.css file, and take a look at it with a text-editor, at the bottom of the file are the areas that you can edit yourself [ with some comments on what they represent ], that way, you can customize it to look anyway you'd like.
Hope this helps! :)