simple execution works

src/App/App.css

@@ -0,0 +1,31 @@
+.layoutVertical {
+  display: flex;
+  flex-direction: column;
+  width: 100%;
+  height: 100vh;
+}
+.panel {
+  height: 1.5rem;
+  background-color: lightgrey;
+}
+.layout {
+  display: flex;
+  width: 100%;
+  height: calc(100vh - 1.5rem);
+}
+
+.sidebar {
+  flex: 0 0 content;
+  padding-right: 4px;
+}
+.content {
+  flex: 1 1 auto;
+  overflow: auto;
+}
+
+details {
+  padding-left :10;
+}
+/* details:not(:has(details)) > summary::marker {
+  color: white;
+} */