Admin theme- Responsive Administration Ips Theme

Admin theme is the most popular contribute Administration Theme for Drupal
Based on the original seven theme, admin theme has several improvements like:

Modern minimalist design that makes administration an easy and fun experience
Responsive layout
Usability Improvements
Per site custom CSS code overrides without the need of hacking or subtheming the main theme
More block positions and up to 3 column main content. So you can have left and right sidebars blocks inside your content page
Colored buttons for common tasks like Submit (Green button), Preview (Blue button), Delete (Red button) etc… So your eye rapidly focuses on the button you want to click
Table highlighting. When you hover your mouse on a table row, it will be highlighted to help you see what goes where
Improved navigation using the Admin theme Menu submodule
And many more …