[libadwaita/wip/exalm/backdrop] stylesheet: Use a flat gradient for backdrop header bar

[Alexander Mikhaylenko <alexm src gnome org>]

commit b7595e3e4a89de3b60428fddc84996a7700f19e1
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Fri Apr 30 17:37:02 2021 +0500

    stylesheet: Use a flat gradient for backdrop header bar
    
    Fixes https://gitlab.gnome.org/GNOME/libadwaita/-/issues/102

 src/stylesheet/widgets/_header-bar.scss | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
---
diff --git a/src/stylesheet/widgets/_header-bar.scss b/src/stylesheet/widgets/_header-bar.scss
index e89a6dc..ea7dc4a 100644
--- a/src/stylesheet/widgets/_header-bar.scss
+++ b/src/stylesheet/widgets/_header-bar.scss
@@ -24,8 +24,7 @@ headerbar {
   }
 
   &:backdrop {
-    background-color: $bg_color;
-    background-image: none;
+    background-image: linear-gradient(to top, $bg_color, $bg_color);
 
     transition: $backdrop_transition;