Show a hint of hidden content under a closed folder

public/custom-style.css

@@ -72,6 +72,12 @@ kbd {
   background: #F9FAFB;
 }
 
+/* Show a hint of hidden content under a closed folder */
+details:not([open]) > summary.ui.top.attached.header {
+  background: linear-gradient(#f9fafb 80%, #ddd 84%, #f9fafb 88%, #ddd 92%, #f9fafb 96%, #ddd);
+  padding-bottom: 1.5rem;
+}
+
 .ui.left.attached.button {
   margin-right: 1px;
 }