[gnome-builder] themes: tweak default omnibar styling

[Christian Hergert <chergert src gnome org>]

commit 392b2021b64707f90224880a3d4e3e01d4a3d665
Author: Christian Hergert <chergert redhat com>
Date:   Thu Jan 31 12:25:42 2019 -0800

    themes: tweak default omnibar styling
    
    This removes some alpha channel usage (in favor of mixing) and alters the
    foreground just slightly.

 src/libide/themes/themes/shared/shared-omnibar.css | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
---
diff --git a/src/libide/themes/themes/shared/shared-omnibar.css 
b/src/libide/themes/themes/shared/shared-omnibar.css
index b59edf131..21f559766 100644
--- a/src/libide/themes/themes/shared/shared-omnibar.css
+++ b/src/libide/themes/themes/shared/shared-omnibar.css
@@ -25,19 +25,24 @@ omnibar notification button {
   box-shadow: none;
   text-shadow: none;
   text-decoration: none;
+  color: alpha(@theme_fg_color, 0.8);
 }
 
 omnibar entry {
-  background-color: @theme_bg_color;
-  color: alpha(@theme_fg_color, 0.8);
+  background-color: mix(@theme_bg_color, @content_view_bg, 0.25);
+  color: @theme_fg_color;
 }
 
 omnibar:hover entry,
 omnibar:active entry {
-  background-color: mix(@theme_bg_color, @content_view_bg, 0.9);
+  background-color: @content_view_bg;
   color: @theme_fg_color;
 }
 
+omnibar:backdrop entry {
+  background-color: @theme_bg_color;
+}
+
 /* Remove animation from linked buttons because it messes up the
  * joined state transition.
  */