Arc Theme is a flat Linux theme with transparent elements for GTK 3, GTK 2 and Gnome-Shell which supports GTK 3 and GTK 2 based desktop environments like Gnome, Unity, Budgie, Pantheon, XFCE, Mate, etc.
Arc Theme Red is A red variation of popular Arc Theme, just like
Linux Mint 18 “Mint-Y” which also based on Arc Theme.
Arc Theme Red has a reduced color range, is mostly gray and red and developed especially for all those who use linux on a Thinkpad.