arc-theme software package provides Flat theme with transparent elements, you can install in your Ubuntu 17.04 (Zesty Zapus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install arc-theme
arc-theme is installed in your system.
Make ensure the arc-theme package were installed using the commands given below,
$ sudo dpkg-query -l | grep arc-theme *
You will get with arc-theme package name, version, architecture and description in a table
| Distro | Ubuntu 17 |
| Section | Miscellaneous |
| Package | arc-theme |
| Version | 20161119-1 |
| Description | Flat theme with transparent elements |
| Sub Section | misc |