Fix #272

Author: lassekongo83

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

@@ -2,6 +2,9 @@
   This file will fix some legacy widget styles that aren't styled in libadwaita
 */
 
+@define-color accent_bg_color @blue_3;
+@define-color accent_fg_color white;
+
 /* add a bg color to notebook headers */
 notebook > header {
   background-color: @headerbar_bg_color;