fix(editor): left-align chapter writing surface

src/renderer/book/editor.ts

@@ -45,6 +45,16 @@ export function createEditorFeature(ctx: BookCtx): EditorFeature {
     onChange: () => handleEditorChange(),
     onSelectionUpdate: () => handleSelection(),
   });
+  const editorHost = $("editorHost");
+
+  // The ProseMirror surface is narrower than its host for readable line
+  // lengths. Keep the surrounding editor area clickable so a new chapter can
+  // be focused without requiring a click on the centered content column.
+  editorHost.addEventListener("mousedown", (event) => {
+    if (event.target !== editorHost) return;
+    event.preventDefault();
+    editor.commands.focus("end");
+  });
 
   // Debounce for automatic saves while typing. When the user stops typing for
   // this long the chapter is persisted in the background so navigating away

src/renderer/index.css

@@ -1665,7 +1665,7 @@ body.focus-mode .editor {
   background: var(--color-bg);
   padding: 24px 20px;
   max-width: 820px;
-  margin: 0 auto;
+  margin: 0;
   outline: none;
 }