// ── 漢堡按鈕 ──
function toggleMobileNav() {
var ham = document.querySelector(".hamburger");
var nav = document.querySelector(".nav-links");
var ov = document.querySelector(".nav-overlay");
if (!ham || !nav) return;
var isOpen = nav.classList.toggle("open");
ham.classList.toggle("active", isOpen);
if (ov) ov.classList.toggle("open", isOpen);
document.body.style.overflow = isOpen ? "hidden" : "";
}