--- a/ui/gtk/toolkit.c	Fri Oct 25 15:44:39 2024 +0200
+++ b/ui/gtk/toolkit.c	Sun Oct 27 08:25:15 2024 +0100
@@ -351,6 +351,9 @@
 ".ui_test {\n"
 "  background-color: red;\n"
 "}\n"
+".ui_label_heading {\n"
+"  font-weight: bold;\n"
+"}\n"
 ;
 
 #elif GTK_MAJOR_VERSION == 3