Fix #232

Author: lassekongo83

gtk/src/adw-gtk3-dark/gtk-3.0/meson.build

@@ -8,3 +8,4 @@ install_subdir('../../adw-gtk3/gtk-3.0/assets', install_dir : gtk3_dark_dir, str
 # Provide a copy of libadwaita as is.
 # In the gtk3 directory so we don't have duplicate the assets.
 install_data(['../../adw-gtk3/gtk-3.0/libadwaita.css'], install_dir: gtk3_dark_dir)
+install_data(['../../adw-gtk3/gtk-3.0/libadwaita-tweaks.css'], install_dir: gtk3_dark_dir)

gtk/src/adw-gtk3-dark/gtk-4.0/gtk-dark.css

@@ -36,3 +36,4 @@
 @define-color scrollbar_outline_color rgba(0, 0, 0, 0.5);
 
 @import '../gtk-3.0/libadwaita.css';
+@import '../gtk-3.0/libadwaita-tweaks.css';

gtk/src/adw-gtk3-dark/gtk-4.0/gtk.css

@@ -36,3 +36,4 @@
 @define-color scrollbar_outline_color rgba(0, 0, 0, 0.5);
 
 @import '../gtk-3.0/libadwaita.css';
+@import '../gtk-3.0/libadwaita-tweaks.css';

gtk/src/adw-gtk3/gtk-3.0/libadwaita-tweaks.css

@@ -0,0 +1,9 @@
+/*
+  This file will fix some legacy widget styles that aren't styled in libadwaita
+*/
+
+/* add a bg color to notebook headers */
+notebook > header {
+  background-color: @headerbar_bg_color;
+  border-color: mix(currentColor,@window_bg_color,0.85);
+}

gtk/src/adw-gtk3/gtk-3.0/meson.build

@@ -51,3 +51,4 @@ endforeach
 # Provide a copy of libadwaita as is.
 # In the gtk3 directory so we don't have duplicate the assets.
 install_data(['libadwaita.css'], install_dir: gtk3_dir)
+install_data(['libadwaita-tweaks.css'], install_dir: gtk3_dir)

gtk/src/adw-gtk3/gtk-4.0/gtk-dark.css

@@ -36,3 +36,4 @@
 @define-color scrollbar_outline_color rgba(0, 0, 0, 0.5);
 
 @import '../gtk-3.0/libadwaita.css';
+@import '../gtk-3.0/libadwaita-tweaks.css';

gtk/src/adw-gtk3/gtk-4.0/gtk.css

@@ -36,3 +36,4 @@
 @define-color scrollbar_outline_color white;
 
 @import '../gtk-3.0/libadwaita.css';
+@import '../gtk-3.0/libadwaita-tweaks.css';