Handle styles for a panel subtitle

scss/elements/_panels.scss

@@ -43,4 +43,12 @@
       padding: 0 ($gap * 4);
     }
   }
+
+  .panel__heading {
+    margin: ($gap * 2) 0;
+
+    h1, h2, h3, h4, h5, h6 {
+      margin: 0;
+    }
+  }
 }