nostalgiaz/bootstrap-toggle-buttons — pull request #19 by zachinglis (2012-10-01 03:06:08+00:00)
Title: Inverted background colour as the skeu suggests.

The skeumorphism says that the slider is embossed which means counteractly behind it, it should be invertedly inset. Thus switching the colours on the gradient around (using the direction) has helped further the idea.