/usr/share/themes/Arc-Dark/xfwm4/themerc is in arc-theme 20180114-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | button_offset=2
button_spacing=4
show_app_icon=true
full_width_title=true
title_shadow_active=false
title_shadow_inactive=false
title_horizontal_offset=3
active_text_color=#afb8c5
active_text_shadow_color=#2f343b
inactive_text_color=#808791
inactive_text_shadow_color=#2f343b
shadow_delta_height=2
shadow_delta_width=0
shadow_delta_x=0
shadow_delta_y=-5
shadow_opacity=40
|