Без перенастройки самой темы.
theme = {}
theme.font = "Terminus 9"
-- bg and fg
local h = io.popen("xrdb -query | grep 'foreground:' | awk '{print $2}'")
x_fg = h:read("*l")
h:close()
local h = io.popen("xrdb -query | grep 'background:' | awk '{print $2}'")
x_bg = h:read("*l")
h:close()
-- black
local h = io.popen("xrdb -query | grep 'color0:' | awk '{print $2}'")
black = h:read("*l")
h:close()
local h = io.popen("xrdb -query | grep 'color8:' | awk '{print $2}'")
l_black = h:read("*l")
h:close()
-- red
local h = io.popen("xrdb -query | grep 'color1:' | awk '{print $2}'")
red = h:read("*l")
h:close()
local h = io.popen("xrdb -query | grep 'color9:' | awk '{print $2}'")
l_red = h:read("*l")
h:close()
-- green
local h = io.popen("xrdb -query | grep 'color2:' | awk '{print $2}'")
green = h:read("*l")
h:close()
local h = io.popen("xrdb -query | grep 'color10:' | awk '{print $2}'")
l_green = h:read("*l")
h:close()
-- yellow
local h = io.popen("xrdb -query | grep 'color3:' | awk '{print $2}'")
yellow = h:read("*l")
h:close()
local h = io.popen("xrdb -query | grep 'color11:' | awk '{print $2}'")
l_yellow = h:read("*l")
h:close()
-- blue
local h = io.popen("xrdb -query | grep 'color4:' | awk '{print $2}'")
blue = h:read("*l")
h:close()
local h = io.popen("xrdb -query | grep 'color12:' | awk '{print $2}'")
l_blue = h:read("*l")
h:close()
-- magenta
local h = io.popen("xrdb -query | grep 'color5:' | awk '{print $2}'")
magenta = h:read("*l")
h:close()
local h = io.popen("xrdb -query | grep 'color13:' | awk '{print $2}'")
l_magenta = h:read("*l")
h:close()
-- cyan
local h = io.popen("xrdb -query | grep 'color6:' | awk '{print $2}'")
cyan = h:read("*l")
h:close()
local h = io.popen("xrdb -query | grep 'color14:' | awk '{print $2}'")
l_cyan = h:read("*l")
h:close()
-- white
local h = io.popen("xrdb -query | grep 'color7:' | awk '{print $2}'")
white = h:read("*l")
h:close()
local h = io.popen("xrdb -query | grep 'color15:' | awk '{print $2}'")
l_white = h:read("*l")
h:close()
theme.bg_normal = x_fg
theme.bg_focus = x_fg
theme.bg_urgent = x_fg
theme.bg_minimize = x_fg
theme.bg_systray = x_fg
theme.fg_normal = x_bg
theme.fg_focus = l_magenta
theme.fg_urgent = l_red
theme.fg_minimize = l_black
theme.border_width = 0
theme.border_normal = l_white
theme.border_focus = white
theme.border_marked = l_black
theme.taglist_bg_focus = blue
theme.taglist_fg_occupied = l_white
theme.taglist_fg_empty = l_black
Найдено здесь.