diff --git a/src/app/story_bible_editor.rs b/src/app/story_bible_editor.rs
index 1b94ea8..862f70a 100644
--- a/src/app/story_bible_editor.rs
+++ b/src/app/story_bible_editor.rs
@@ -231,11 +231,16 @@ impl App {
         // that borrow `self` have finished.
         let mut focused = false;
         ui.horizontal(|ui| {
-            // Left panel: Tree view (1/3 width)
+            // Left panel: Tree view (1/3 width). The width must be set on
+            // this panel's own child `Ui`, not the shared horizontal one —
+            // that had been shrinking the whole row (tree, separator, and
+            // the editor panel with it) down to a third of the window,
+            // which is why the editor's heading used to wrap one letter at
+            // a time.
             let tree_width = ui.available_width() / 3.0;
-            ui.set_width(tree_width);
-            
+
             ui.vertical(|ui| {
+                ui.set_width(tree_width);
                 ui.heading("Story Bible");
                 ui.separator();