Source (link to git-repo or to original if based on someone elses unmodified work): https://github.com/rtlewis88/rtl88-Themes/tree/material-black-MAGIC
material-black MAGIC is a new GTK, xfwm4, openbox-3, GNOME-Shell, and Cinnamon dark mode theme with many transparent elements.
The material-black MAGIC theme is based on Material Design standards and aims to bring a warm, colorful, and elegant experience to your desktop. Black-on-black-on-black with one additional color just where you need it. Even more semi-transparent elements on the shells. Have some fun!
Manual Installation Is Easy:
Extract the "tar.xz" file into your "~/.themes/" folder - to install for current user only - or into the "/usr/share/themes/" folder - for the theme to be applied globally. 2) Use the GNOME Tweak Tool or an equivalent app to enable it for your desktop.
If installing manually, make sure to install the dependency: "Murrine theme engine" if you do not already have it; and update your GTK+packages if you have not.
Logging out and then logging back in may be necessary on some operating systems to fully implement themes.