/usr/share/themes/Xfce-stellar/gtk-2.0/gtkrc is in gtk2-engines-xfce 3.2.0-2.
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 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 | style "default"
{
    GtkButton::default_border         = {5, 5, 5, 5}
    GtkButton::default_outside_border = {6, 6, 6, 6}
    GtkButton::default_spacing        = 5
    GtkButton::focus-padding          = 0
    GtkCheckButton::indicator_size    = 15
    GtkRadioButton::indicator_size    = 15
    GtkMenuItem::selected_shadow_type = in
    GtkPaned::handle_full_size        = 1
    GtkRange::slider_width            = 12
    GtkRange::stepper_size            = 12
    GtkRange::stepper_spacing         = 0
    GtkRange::trough_border           = 0
    GtkScrollbar::min_slider_length   = 20
    GtkWidget::focus-line-pattern     = "\0"
    GtkWidget::focus-line-width       = 2
    GtkWidget::interior_focus         = 0
    GtkWidget::internal-padding       = 2
    ExoIconBar::active-item-border-color = "#724056"
    ExoIconBar::active-item-fill-color = "#b24d7a"
    ExoIconBar::active-item-text-color = "#ffffff"
    ExoIconBar::cursor-item-border-color = "#707481"
    ExoIconBar::cursor-item-fill-color = "#AEB2C3"
    ExoIconBar::cursor-item-text-color = "#000000"
    xthickness = 1
    ythickness = 1
    fg[NORMAL]       = "#000000"
    fg[ACTIVE]       = "#000000"
    fg[PRELIGHT]     = "#000000"
    fg[SELECTED]     = "#ffffff"
    fg[INSENSITIVE]  = "#4e4f56" 
    bg[NORMAL]       = "#aeb2c3"
    bg[ACTIVE]       = "#9ba0b0"
    bg[PRELIGHT]     = "#aeb2c3"
    bg[SELECTED]     = "#b24d7a"
    bg[INSENSITIVE]  = "#9ba0b0"
    base[NORMAL]     = "#fcfcf0"
    base[SELECTED]   = "#b24d7a"
    base[ACTIVE]     = "#888ca0"
    base[PRELIGHT]   = "#b24d7a"
    base[INSENSITIVE]= "#969bb4"
    text[INSENSITIVE]= "#747474"
    text[NORMAL]     = "#000000"
    text[ACTIVE]     = "#000000"
    text[PRELIGHT]   = "#000000"
    text[SELECTED]   = "#ffffff"
    engine "xfce"
    {
        grip_style = none
        smooth_edge = true
    }
}
style "menu" = "default"
{
    bg[PRELIGHT]     = "#9BA0B0" 
    text[PRELIGHT]   = "#FFFFFF"
}
class "GtkWidget"    style "default"
class "GtkMenuItem*" style "menu"
# This is for ROX-Filer
# 
style "rox" = "default"
{
  bg[NORMAL] = "#ffffff"
  bg[ACTIVE] = "#ffffff"
}
widget_class "*Collection" style "rox"
# This is for the window borders (xfwm4 & metacity)
# 
style "titlebar" = "default"
{
    bg[SELECTED]      = "#b24d7a"
    fg[SELECTED]      = "#ffffff"
    bg[INSENSITIVE]   = "#9ba0b0"
    fg[INSENSITIVE]   = "#000000"
}
widget "xfwm"	          style "titlebar"
class "MetaFrames"        style "titlebar"
widget_class "MetaFrames" style "titlebar"
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