Dark Material came out with over 80+ themed apps and lots of system tweaks. It makes you flat and well-designed interface with many rounded icons. It allows you to choose the color of the accent. In some parts of the interface, it also has a super cool background design. It also supports a lot of third party applications. It will work on Torrone, Oreo and Torta. This theme is based on Pixel and Aosp Rom. Please contact me before posting negative reviews or comments. We both can improve things personally, trust me.
Supported Android Devices : [7.0 – 7.1.1] Nougat – [8.0-8.1] Oreo –  Pie