Change the theme of the root user easily in Ubuntu

You should need a program called "Ubuntu Tweak" to do the trick easily. Get it from here.  After installing it Go to Applications --> System tools -->  Ubuntu Tweak.  Then go to Security Related (in System ). In there under Miscellaneous options you'll find an option Fix appearance of programs when granted root privileges( If the option is greyd out click on "unlock" in the bottom and enter the root password). Tick it and everything is done ..!