/usr/share/afterstep/ucf/gtkrc_template is in afterstep-data 2.2.12-11.1.
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 24 25 26 27 28 29 30 31 32 33 34 35  | # Edit these colors and fonts however you like.
style "default"
{
	fg[NORMAL]         =    "InactiveText1"   	
	fg[ACTIVE]         =    "InactiveText2"   	
	fg[PRELIGHT]       =    "HighInactiveText"	
	fg[SELECTED]       =    "ActiveText"      	
	fg[INSENSITIVE]	   =    "DisabledText"    	
	bg[NORMAL]         =   	"Inactive1"       	
	bg[ACTIVE]         =   	"Inactive2"   		
	bg[PRELIGHT]       =  	"HighInactive"		
	bg[SELECTED]       =  	"Active"	  	
	bg[INSENSITIVE]    = 	"Inactive1"   		
	text[NORMAL]       = 	"InactiveText1"   	
	text[ACTIVE]       = 	"InactiveText2"   	
	text[PRELIGHT]     = 	"HighInactiveText"	
	text[SELECTED]     = 	"ActiveText"		
	text[INSENSITIVE]  = 	"InactiveText1"   	
	base[NORMAL]       = 	"Inactive1"   		
	base[ACTIVE]       = 	"Inactive2"   		
	base[PRELIGHT]     = 	"HighInactive"		
	base[SELECTED]     = 	"Active"	  	
	base[INSENSITIVE]  = 	"Inactive1"   		
	engine "clearlooks"  {
	       menubarstyle      = 2       # 0 = flat, 1 = sunken, 2 = flat gradient
               menuitemstyle     = 1       # 0 = flat, 1 = 3d-ish (gradient), 2 = 3d-ish (button)
               listviewitemstyle = 1       # 0 = flat, 1 = 3d-ish (gradient)
               progressbarstyle  = 0       # 0 = candy bar, 1 = flat
	}
}
class "GtkWidget" style "default"
 |