Install with modgit:
$ cd /path/to/magento
$ modgit init
$ modgit clone admin-theme https://github.com/jreinke/magento-admin-theme.git
or download package manually:
- Download latest version here
- Logout from admin
- Unzip in Magento root folder
- Clear cache
- Login to admin
Switch theme from dropdown added in footer.
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