Just a modified elementary theme adding transparency to Wingpanel, it's indicators and Slingshot.
Open a terminal and add the following ppa ( Personal Package Archive ) :
sudo add-apt-repository ppa:yunnxx/elementary
sudo apt-get update
sudo apt-get install elementary-transparent-theme
Go to System Settings > Tweaks > Appearance and change Window Decoration Theme and Interface Theme to transparent.
For installing Tweaks see my former post....
Log out and in again....