diff --git a/gp2040ce_bintools/config_tree.css b/gp2040ce_bintools/config_tree.css
index 90cb8cd..87c61a5 100644
--- a/gp2040ce_bintools/config_tree.css
+++ b/gp2040ce_bintools/config_tree.css
@@ -20,6 +20,12 @@ EditScreen Label {
     content-align: center middle;
 }
 
+#config_tree {
+    border: heavy gray;
+    padding: 1;
+    margin: 1;
+}
+
 .hidden {
     visibility: hidden;
 }
diff --git a/gp2040ce_bintools/gui.py b/gp2040ce_bintools/gui.py
index b8f957b..3dd7b08 100644
--- a/gp2040ce_bintools/gui.py
+++ b/gp2040ce_bintools/gui.py
@@ -141,7 +141,7 @@ class ConfigEditor(App):
         """Compose the UI."""
         yield Header()
         yield Footer()
-        yield Tree("Root")
+        yield Tree("Root", id='config_tree')
 
     def on_mount(self) -> None:
         """Load the configuration object into the tree view."""