diff --git a/ui/src/components/ui/NavBar.vue b/ui/src/components/ui/NavBar.vue
index c9d8a52..b21d26d 100644
--- a/ui/src/components/ui/NavBar.vue
+++ b/ui/src/components/ui/NavBar.vue
@@ -79,7 +79,11 @@ const handleLinkClick = () => {
     <!-- encabezado dentro de sidebar -->
     <div class="flex items-center justify-between px-4 py-4 md:px-5 md:py-4 md:border-none"
          style="border-bottom-color: var(--secondary-color); border-bottom-width: 1px;">
-      <!-- Intentionally left empty to preserve spacing on mobile -->
+      <!-- preserve spacing where the 'Núcleo' title used to be -->
+      <button class="close-btn h-8 w-8 flex items-center justify-center rounded-full border transition duration-200"
+              @click="ui.toggleSidebar">
+        ✕
+      </button>
     </div>
 
     <!-- navegación -->