diff --git a/frontend/js/pane-manager.js b/frontend/js/pane-manager.js
index 561a5fc..1686f9b 100644
--- a/frontend/js/pane-manager.js
+++ b/frontend/js/pane-manager.js
@@ -481,6 +481,13 @@ const PaneManager = {
     this.tabManagers[0] = createPaneTabManager(0);
     this.tabManagers[0].init();
 
+    // Setup drop zone on content-wrapper for single-pane drag-to-split
+    const wrapper = document.querySelector('.content-wrapper');
+    if (wrapper && !wrapper.dataset.dropZoneSetup) {
+      wrapper.dataset.dropZoneSetup = '1';
+      this._setupPaneDropZone(wrapper, 0);
+    }
+
     const saved = localStorage.getItem('obsigate-panes');
     if (saved) {
       try {
diff --git a/frontend/style.css b/frontend/style.css
index 2a84a3e..5dee4ad 100644
--- a/frontend/style.css
+++ b/frontend/style.css
@@ -1245,6 +1245,7 @@ select {
   flex-direction: column;
   min-width: 0;
   overflow: hidden;
+  position: relative;
 }
 
 /* --- Multi-Pane Grid (Split View #75) --- */