[gtksourceview] tango.xml, classic.xml: tweak line-number styling

[Christian Hergert <chergert src gnome org>]

commit 2c8d4a88c560f606a311ed1f070fc14e958d9463
Author: Christian Hergert <chergert redhat com>
Date:   Mon Jan 27 13:16:51 2020 -0800

    tango.xml, classic.xml: tweak line-number styling
    
    Since Adwaita 3.24, the styling for the gutters has been less dramatic.
    As this GtkSourceView style scheme does not specify a line-number
    background, very little contrast was available.
    
    Since this style-scheme needs to be rather agnostic in terms of GTK
    theme, we can use an RGBA style to overlay similar to the right margin.
    It's not perfect, but it fixes the typical case without causing too
    much pain for the other cases.
    
    In the future we may want to provide a strategy for GTK theme agnostic
    style-schemes to pull values from the GTK theme directly (or mix() between
    values).
    
    Fixes #102

 data/styles/classic.xml | 1 +
 data/styles/tango.xml   | 1 +
 2 files changed, 2 insertions(+)
---
diff --git a/data/styles/classic.xml b/data/styles/classic.xml
index 379ede77..183f5881 100644
--- a/data/styles/classic.xml
+++ b/data/styles/classic.xml
@@ -42,6 +42,7 @@
   <color name="purple"     value="#A020F0"/>
 
   <!-- Global Settings -->
+  <style name="line-numbers"                background="#rgba(0,0,0,0.005)"/>
   <style name="current-line"                background="#eeeeec"/>
   <style name="current-line-number"         background="#eeeeec"/>
   <style name="draw-spaces"                 foreground="#babdb6"/>
diff --git a/data/styles/tango.xml b/data/styles/tango.xml
index 4fbd2c33..6b272176 100644
--- a/data/styles/tango.xml
+++ b/data/styles/tango.xml
@@ -54,6 +54,7 @@
   <color name="aluminium6"                  value="#2e3436"/>
 
   <!-- Global Settings -->
+  <style name="line-numbers"                background="#rgba(18,20,21,0.005)"/>
   <style name="current-line"                background="aluminium1"/>
   <style name="current-line-number"         background="aluminium1"/>
   <style name="draw-spaces"                 foreground="aluminium3"/>