[gtksourceview] classic: improve grid color styling

[Christian Hergert <chergert src gnome org>]

commit 54fdd49341c09a9a62bfce3a1ca23ea7826d9279
Author: Christian Hergert <chergert redhat com>
Date:   Mon Dec 9 12:24:42 2019 -0800

    classic: improve grid color styling
    
    The classic style is used by default and therefore needs to have
    a reasonably good look on a number of GTK themes. This uses an
    alpha channel to draw the grid so that we are less likely to
    have a garish view.
    
    The style is .1 alpha of the draw-spaces color.
    
    Fixes #98

 data/styles/classic.xml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/data/styles/classic.xml b/data/styles/classic.xml
index 384deac0..379ede77 100644
--- a/data/styles/classic.xml
+++ b/data/styles/classic.xml
@@ -45,7 +45,7 @@
   <style name="current-line"                background="#eeeeec"/>
   <style name="current-line-number"         background="#eeeeec"/>
   <style name="draw-spaces"                 foreground="#babdb6"/>
-  <style name="background-pattern"          background="#f3f3f3"/>
+  <style name="background-pattern"          background="#rgba(73,74,71,0.1)"/>
 
   <!-- Bracket Matching -->
   <style name="bracket-match"               foreground="white" background="gray"/>