fix(workspace): more room for notes on phones

Almost no side margin, 14 px indent per level (22 px from tablet width
on), zoom and delete buttons only take width in the active row. Very deep
rows keep about 14rem and the note scrolls sideways instead of squeezing
the text.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/index.css

@@ -549,3 +549,16 @@ fieldset:disabled :is(button, input, select, textarea) {
   opacity: 0.5;
   cursor: not-allowed;
 }
+
+/* Outliner: indent per level and the width a row keeps for its text. Phones indent less and let very
+   deep rows run wider than the screen (the note then scrolls sideways) instead of squeezing the text. */
+:root {
+  --outline-indent: 14px;
+  --outline-min-text: 14rem;
+}
+@media (min-width: 640px) {
+  :root {
+    --outline-indent: 22px;
+    --outline-min-text: 0px;
+  }
+}