diff --git a/CLAUDE.md b/CLAUDE.md
index 3fc08de..9f21de9 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -13,6 +13,7 @@
 - use Vue.js as a framework
 - use Bootstrap or Quasar for CSS/UI. Load via CDN script tags, not npm.
 - no JS testing framework for now. Do not add Jest, Vitest, or similar unless asked.
+- do not use var constructions in most circumstances. Prefer let and const.
 
 ## HTML/CSS
 - use semantic HTML elements (`<nav>`, `<main>`, `<header>`, `<button>`, `<form>`) instead of generic `<div>` and `<span>`.