Rewrite navbar (#1154)

Fixes #877, #872

assets/js/main.js

@@ -0,0 +1,27 @@
+//
+// Navbar dropdowns
+//
+
+const navSections = document.querySelectorAll(".nav-details");
+
+navSections.forEach(navSection => {
+  navSection.addEventListener("toggle", navSectionsToggle);
+});
+document.addEventListener("click", navSectionsClose);
+
+function navSectionsToggle() {
+  // When opening next dropdown, hide previous
+  if (this.open) {
+    navSections.forEach(navSection => {
+      if (navSection != this && navSection.open) navSection.open = !open;
+    });
+  }
+}
+
+function navSectionsClose(event) {
+  // Hide all dropdowns when clicking in different place
+  if (event.target.matches(".nav-summary")) return;
+  navSections.forEach(navSection => {
+    navSection.open = !open;
+  });
+}