✨ distraction free mode

src/renderer/styles/app.css

@@ -4,7 +4,44 @@
   grid-template-rows: 38px calc(100vh - 38px);
   height: 100vh;
   overflow: hidden;
-  transition: grid-template-columns 0.2s ease;
+  transition: grid-template-columns 0.25s ease, grid-template-rows 0.25s ease;
+}
+
+/* ─── Focus / distraction-free mode ───────────────────────────── */
+.app-layout[data-focus='on'] {
+  grid-template-columns: 0 1fr 0;
+  grid-template-rows: 0 100vh;
+}
+
+.app-layout[data-focus='on'] .app-titlebar {
+  overflow: hidden;
+  border: none;
+}
+
+.app-layout[data-focus='on'] .toolbar {
+  display: none;
+}
+
+.focus-exit-btn {
+  position: fixed;
+  top: 10px;
+  right: 14px;
+  z-index: 9999;
+  background: none;
+  border: 1px solid var(--border);
+  color: var(--text-muted);
+  font-size: 13px;
+  padding: 3px 7px;
+  border-radius: 4px;
+  cursor: pointer;
+  opacity: 0.12;
+  transition: opacity 0.2s;
+  -webkit-app-region: no-drag;
+}
+
+.focus-exit-btn:hover {
+  opacity: 0.6;
+  color: var(--text-primary);
 }
 
 .app-layout[data-sidebar='closed'] {