Administration themes are used to control colors and images in the Bigace administration.
Why? Because you might need to create special themes for your customers (e.g. for accessibility reasons) and because its just fun ;-)
Creating a new theme is easy if you know CSS, as a theme is not more than a CSS file:
opy the file ''/public/system/admin/css/theme_blue.css'' to ''/public/system/admin/css/theme_new.css''
Adjust the CSS settings in ''theme_new.css'' and save the file
Go to bigace:manual:configurations and change the key "admin/theme" from "theme_blue" to "theme_new"
Enjoy your new theme