Mantis

Mantis is a dark gray theme for Xfce.
It's existence comes from a need for an easy-on-the-eyes workstation theme.

The GTK 2 widget theme is based on Xfce-Simple-Dark (https://github.com/trustable-code/Xfce-Simple-Dark)
Basic GTK3 support exists and is lifted from my dark gray spin of the Arc theme (https://github.com/mantissa-/arc-pro-theme)

Xfce panel theming needs some work, but it's not the worst.

Tested on Xubuntu 17.10, YMMV.

Breeze icon set was used in this setup

Installation

Unzip and rename base folder Mantis, then copy into your ~/.themes/ directory.
Open Appearance and select the theme.
Open Window Manager and select the theme.

GPLv3