// 响应式导航（home / ai / competition_list / aboutus 共用）：
// 页面在 header 内放置 <button class="nav-toggle">，≤960px 时显示汉堡按钮，
// 点击切换 header.nav-open，CSS 控制折叠面板与 .nav-backdrop 遮罩。
(function () {
    function initNavResponsive() {
        var toggles = document.querySelectorAll('.nav-toggle');
        if (!toggles.length) return;

        function syncBody() {
            document.body.classList.toggle('nav-open', !!document.querySelector('header.nav-open'));
        }

        function setOpen(header, btn, open) {
            header.classList.toggle('nav-open', open);
            btn.setAttribute('aria-expanded', open ? 'true' : 'false');
            btn.setAttribute('aria-label', open ? '关闭菜单' : '打开菜单');
            syncBody();
        }

        toggles.forEach(function (btn) {
            var header = btn.closest('header');
            if (!header || header.dataset.navReady) return;
            header.dataset.navReady = '1';

            var backdrop = document.createElement('div');
            backdrop.className = 'nav-backdrop';
            header.appendChild(backdrop);

            btn.addEventListener('click', function (e) {
                e.stopPropagation();
                setOpen(header, btn, !header.classList.contains('nav-open'));
            });
            backdrop.addEventListener('click', function () {
                setOpen(header, btn, false);
            });
            header.addEventListener('click', function (e) {
                if (e.target.closest('.nav__links a, .nav-list a, .navbar-collapse a, .navbar-logout')) {
                    setOpen(header, btn, false);
                }
            });
            document.addEventListener('keydown', function (e) {
                if (e.key === 'Escape') setOpen(header, btn, false);
            });
            window.addEventListener('resize', function () {
                if (window.innerWidth > 960) setOpen(header, btn, false);
            });
        });
    }

    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', initNavResponsive);
    } else {
        initNavResponsive();
    }
})();