theme: tone down unfocused title labels

- mimic libadwaita in toning down unfocused titles. Cargo culting the
  filter instead of using normal opacity property.

Fixes https://gitlab.gnome.org/GNOME/gtk/-/issues/4468

diff --git a/gtk/theme/Default/_common.scss b/gtk/theme/Default/_common.scss
index ea7415faf28c0d2d99ead5355c3d5669e5a54b52..d627cf9674bb2cd67c90a6f20e86511aa5742cdd 100644 (file)
--- a/gtk/theme/Default/_common.scss
+++ b/gtk/theme/Default/_common.scss
@@ -1500,6 +1500,8 @@ headerbar {
     background-image: none;
 
     transition: $backdrop_transition;
+
+    .title { filter: opacity(.5); }
   }
 
   .title {