Since I use Symphony for the bulk of my web + client projects, I thought it would be nice to have a better admin theme. This is a work in progress.
I've moved all of the core Symphony CSS files and Devkit CSS files over here and setup a repository to work on these files. It is a work in progress right now. The goal is to redo the entire Symphony Core CSS responsively in Sass to minimize back-end bloat and improve the overall user experience.
To compile the Sass files using the included Grunt configuration, just ensure that you have NodeJS and Grunt 0.4.1 installed globally installed globally.
Feel free to fork this and improve it. Eventually if this style gets developed far enough along, Symphony Core may pick it up and implement it as the main admin theme!