[gtk/wip/jimmac/button-shed: 4/4] Adwaita: special case flat headerbar buttons

[Jakub Steiner <jimmac src gnome org>]

commit f6f624162708fbd761b54e3ca37f94aac4ec0f3d
Author: Jakub Steiner <jimmac gmail com>
Date:   Thu Dec 10 14:24:29 2020 +0100

    Adwaita: special case flat headerbar buttons
    
    - make sure the hovers and pushed states are legible on a tintend headerbar
    
    Fixes https://gitlab.gnome.org/GNOME/gtk/-/issues/3427

 gtk/theme/Adwaita/_common.scss | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/gtk/theme/Adwaita/_common.scss b/gtk/theme/Adwaita/_common.scss
index 1d2f8b6396..845582650d 100644
--- a/gtk/theme/Adwaita/_common.scss
+++ b/gtk/theme/Adwaita/_common.scss
@@ -1389,11 +1389,17 @@ windowcontrols {
 
     @extend %button_basic_flat;
 
+
     border-radius: 9999px;
     padding: 6px;
     margin: 0 2px;
     min-width: 0;
     min-height: 0;
+    &:hover {
+      //special case hover colors inside a headerbar
+      @include button(undecorated-hover,$c:$headerbar_bg_color);
+    }
+    &:active { @include button(undecorated-active,$c:$headerbar_bg_color); }
   }
 }