Burg themes won't install on Ubuntu 16.04, after adding the repository and trying to run apt-get update it just fails with "Failed to fetch http://ppa.launchpad.net/n-muench/burg/ubuntu/dists/yakkety/main/binary-amd64/Packages 404 Not Found" And I can't get through this to install any themes.
Burg team has stopped its development and installing it on newer ubuntu versions is buggy.
I suggest you to continue using grub. Actually there are many good themes existing for grub. A few of them are