Refine white notification card text via card variant token cascade

styles/40-components-cards.css

@@ -111,8 +111,8 @@
   background: var(--surface-object-card-lower-segment);
 }
 
-.sg-card-segment--text-dark {
-  color: var(--text-card-body);
+.sg-card.sg-card--notification-white {
+  --text-card-header: var(--text-card-body);
 }
 
 .sg-card--content-card {