[gtksourceview] tango.xml: add background and foreground colors

[Christian Hergert <chergert src gnome org>]

commit 0ce1d669a649cacf431b1d5e9b08847f87633161
Author: Christian Hergert <chergert redhat com>
Date:   Mon Oct 11 17:52:43 2021 -0700

    tango.xml: add background and foreground colors
    
    This fixes a longstanding issue with things looking incorrect based on the
    widget toolkit. This provides consistency and can be used with future APIs
    to select the idea variant (oblivion) for dark theme situations.

 data/styles/tango.xml | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/data/styles/tango.xml b/data/styles/tango.xml
index cd6f97da..eaa68ca9 100644
--- a/data/styles/tango.xml
+++ b/data/styles/tango.xml
@@ -25,6 +25,8 @@
   <_description>Color scheme using Tango color palette</_description>
 
   <!-- Tango Palette -->
+  <color name="white"                       value="#FFFFFF"/>
+  <color name="black"                       value="#000000"/>
   <color name="butter1"                     value="#fce94f"/>
   <color name="butter2"                     value="#edd400"/>
   <color name="butter3"                     value="#c4a000"/>
@@ -53,8 +55,10 @@
   <color name="aluminium5"                  value="#555753"/>
   <color name="aluminium6"                  value="#2e3436"/>
 
+  <style name="text"                        foreground="black" background="white"/>
+
   <!-- Global Settings -->
-  <style name="line-numbers"                background="#rgba(18,20,21,0.005)"/>
+  <style name="line-numbers"                background="aluminium1"/>
   <style name="current-line"                background="aluminium1"/>
   <style name="current-line-number"         background="aluminium1"/>
   <style name="draw-spaces"                 foreground="aluminium3"/>