[libadwaita/wip/exalm/background-colors: 35/48] stylesheet: Redo GtkExpander hover

[Alexander Mikhaylenko <alexm src gnome org>]

commit 2a1a460d6bcf15bf854b86266f1b8c698c0f2e9a
Author: Alexander Mikhaylenko <alexm gnome org>
Date:   Wed Sep 1 13:58:02 2021 +0500

    stylesheet: Redo GtkExpander hover
    
    Match expanders in lists/trees instead, make sure it's recolorable.

 src/stylesheet/widgets/_expanders.scss | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/src/stylesheet/widgets/_expanders.scss b/src/stylesheet/widgets/_expanders.scss
index 42b76874..658271fc 100644
--- a/src/stylesheet/widgets/_expanders.scss
+++ b/src/stylesheet/widgets/_expanders.scss
@@ -4,7 +4,7 @@ expander {
   -gtk-icon-source: -gtk-icontheme('pan-end-symbolic');
   &:dir(rtl) { -gtk-icon-source: -gtk-icontheme('pan-end-symbolic-rtl'); }
 
-  &:disabled { opacity: .5; }
+  &:disabled { filter: opacity(.5); }
 
   &:checked { -gtk-icon-source: -gtk-icontheme('pan-down-symbolic'); }
 }
@@ -16,8 +16,12 @@ expander-widget {
     transition: $focus_transition;
     border-radius: $button_radius;
 
+    > expander {
+      opacity: .7;
+    }
+
     &:hover > expander {
-      color: lighten($fg_color,30%); //only lightens the icon
+      opacity: 1;
     }
   }
 }