diff --git a/internal/web/static/jump.js b/internal/web/static/jump.js
index 03fb611..cb1574b 100644
--- a/internal/web/static/jump.js
+++ b/internal/web/static/jump.js
@@ -38,4 +38,14 @@
   window.addEventListener('resize', refresh);
   if (scroller !== window && scroller) scroller.addEventListener('input', refresh);
   refresh();
+  /* #282: the first evaluation can run before the layout settles (media
+     queries, web fonts, async highlighting) and under-measure the content,
+     leaving the nav hidden on long pages. Re-check once a real layout exists
+     and after load; the ResizeObserver also catches late content growth. */
+  requestAnimationFrame(function () { requestAnimationFrame(refresh); });
+  window.addEventListener('load', refresh);
+  window.setTimeout(refresh, 300);
+  if (window.ResizeObserver && scroller === window && document.body) {
+    new ResizeObserver(refresh).observe(document.body);
+  }
 })();