Vallis is a free Joomla! ® 2.5-Style Administrator Template for Joomla! 3.x. It is fully Responsive and has 3 color options (Blue, Red and Green). Vallis is the Joomla! 3 admin template based on Bootstrap
from Twitter and the launch of the Joomla User Interface library (JUI). If you are missing Joomla! 2.5 Admin Panel you can use Vallis.