fix: responsive mega menu

static/css/main.css

@@ -2926,15 +2926,50 @@ a.citation-count-badge:hover {
     font-size: 0.95rem;
   }
 
+  .nav-item.has-megamenu:hover .nav-arrow {
+    transform: none;
+  }
+
+  .nav-item.has-megamenu.open .nav-arrow {
+    transform: rotate(180deg);
+  }
+
   .megamenu {
     position: static;
-    background: rgba(255, 255, 255, 0.03);
-    border: 1px solid var(--glass-border);
+    max-height: 0;
+    overflow: hidden;
+    margin: 0;
+    padding: 0;
+    border: none;
     border-radius: var(--radius-md);
     transform: none;
     box-shadow: none;
     backdrop-filter: none;
     -webkit-backdrop-filter: none;
+    opacity: 0;
+    visibility: hidden;
+    pointer-events: none;
+  }
+
+  .nav-item.has-megamenu:hover .megamenu {
+    opacity: 0;
+    visibility: hidden;
+    max-height: 0;
+    pointer-events: none;
+    transform: none;
+  }
+
+  .nav-item.has-megamenu.open .megamenu {
+    max-height: 2000px;
+    overflow: visible;
+    margin-top: 0.25rem;
+    padding: 0;
+    background: rgba(255, 255, 255, 0.03);
+    border: 1px solid var(--glass-border);
+    opacity: 1;
+    visibility: visible;
+    pointer-events: auto;
+    transform: none;
   }
 
   .megamenu-inner {
@@ -2956,14 +2991,28 @@ a.citation-count-badge:hover {
     max-width: none;
   }
 
-  .megamenu-product-item.has-subproducts .megamenu-sublist {
-    max-height: none;
-    opacity: 1;
-    border-top-color: var(--glass-border);
+  .megamenu-product-item.has-subproducts:hover .megamenu-sub-chevron,
+  .megamenu-product-item.has-subproducts:focus-within .megamenu-sub-chevron {
+    transform: none;
+    color: var(--text-muted);
   }
 
-  .nav-item.has-megamenu:hover .megamenu {
-    transform: none;
+  .megamenu-product-item.has-subproducts:hover .megamenu-sublist,
+  .megamenu-product-item.has-subproducts:focus-within .megamenu-sublist {
+    max-height: 0;
+    opacity: 0;
+    border-top-color: transparent;
+  }
+
+  .megamenu-product-item.has-subproducts.open .megamenu-sub-chevron {
+    transform: rotate(180deg);
+    color: var(--accent-blue-light);
+  }
+
+  .megamenu-product-item.has-subproducts.open .megamenu-sublist {
+    max-height: 320px;
+    opacity: 1;
+    border-top-color: var(--glass-border);
   }
 
   .sub-product-grid {

static/js/main.js

@@ -12,6 +12,12 @@ const SELECTORS = {
   citationCopy: '.citation-copy',
 };
 
+const MOBILE_NAV_MQ = window.matchMedia('(max-width: 768px)');
+
+function isMobileNav() {
+  return MOBILE_NAV_MQ.matches;
+}
+
 function initNavbarScroll() {
   const navbar = document.querySelector(SELECTORS.navbar);
   if (!navbar) return;
@@ -28,6 +34,26 @@ function initNavbarScroll() {
   onScroll();
 }
 
+function closeMobileNavMenu() {
+  const toggle = document.querySelector(SELECTORS.navbarToggle);
+  const menu = document.querySelector(SELECTORS.navbarMenu);
+  const productsItem = document.querySelector(SELECTORS.productsNavItem);
+  if (!toggle || !menu) return;
+
+  menu.classList.remove('open');
+  toggle.classList.remove('open');
+  toggle.setAttribute('aria-expanded', 'false');
+
+  if (productsItem) {
+    productsItem.classList.remove('open');
+    const productsTrigger = productsItem.querySelector('.nav-link');
+    if (productsTrigger) productsTrigger.setAttribute('aria-expanded', 'false');
+    productsItem.querySelectorAll('.megamenu-product-item.has-subproducts.open').forEach((item) => {
+      item.classList.remove('open');
+    });
+  }
+}
+
 function initMobileMenu() {
   const toggle = document.querySelector(SELECTORS.navbarToggle);
   const menu = document.querySelector(SELECTORS.navbarMenu);
@@ -37,22 +63,26 @@ function initMobileMenu() {
     const isOpen = menu.classList.toggle('open');
     toggle.classList.toggle('open', isOpen);
     toggle.setAttribute('aria-expanded', String(isOpen));
+    if (!isOpen) {
+      const productsItem = document.querySelector(SELECTORS.productsNavItem);
+      if (productsItem) {
+        productsItem.classList.remove('open');
+        const productsTrigger = productsItem.querySelector('.nav-link');
+        if (productsTrigger) productsTrigger.setAttribute('aria-expanded', 'false');
+      }
+    }
   });
 
   document.addEventListener('keydown', (e) => {
     if (e.key === 'Escape' && menu.classList.contains('open')) {
-      menu.classList.remove('open');
-      toggle.classList.remove('open');
-      toggle.setAttribute('aria-expanded', 'false');
+      closeMobileNavMenu();
       toggle.focus();
     }
   });
 
   document.addEventListener('click', (e) => {
     if (!menu.contains(e.target) && !toggle.contains(e.target)) {
-      menu.classList.remove('open');
-      toggle.classList.remove('open');
-      toggle.setAttribute('aria-expanded', 'false');
+      closeMobileNavMenu();
     }
   });
 }
@@ -80,18 +110,21 @@ function initMegaMenu() {
   }
 
   function openMenu() {
+    if (isMobileNav()) return;
     cancelClose();
     productsItem.classList.add('open');
     trigger.setAttribute('aria-expanded', 'true');
   }
 
   function beginClose() {
+    if (isMobileNav()) return;
     productsItem.classList.remove('open');
     trigger.setAttribute('aria-expanded', 'false');
     megamenu.classList.add('is-closing');
   }
 
   function scheduleClose(event) {
+    if (isMobileNav()) return;
     if (event && isPointerInMenu(event.relatedTarget)) return;
 
     clearTimeout(hideTimer);
@@ -111,9 +144,21 @@ function initMegaMenu() {
   megamenu.addEventListener('mouseenter', openMenu);
   megamenu.addEventListener('mouseleave', scheduleClose);
 
+  trigger.addEventListener('click', (e) => {
+    if (!isMobileNav()) return;
+    e.preventDefault();
+    const isOpen = productsItem.classList.toggle('open');
+    trigger.setAttribute('aria-expanded', String(isOpen));
+  });
+
   trigger.addEventListener('keydown', (e) => {
     if (e.key === 'Enter' || e.key === ' ') {
       e.preventDefault();
+      if (isMobileNav()) {
+        const isOpen = productsItem.classList.toggle('open');
+        trigger.setAttribute('aria-expanded', String(isOpen));
+        return;
+      }
       const isOpen = productsItem.classList.toggle('open');
       if (isOpen) {
         openMenu();
@@ -124,10 +169,27 @@ function initMegaMenu() {
       trigger.setAttribute('aria-expanded', String(isOpen));
     }
     if (e.key === 'Escape') {
+      if (isMobileNav()) {
+        productsItem.classList.remove('open');
+        trigger.setAttribute('aria-expanded', 'false');
+        return;
+      }
       cancelClose();
       beginClose();
     }
   });
+
+  productsItem.querySelectorAll('.megamenu-product-item.has-subproducts').forEach((item) => {
+    const link = item.querySelector('.megamenu-product-link');
+    if (!link) return;
+
+    link.addEventListener('click', (e) => {
+      if (!isMobileNav()) return;
+      if (item.classList.contains('open')) return;
+      e.preventDefault();
+      item.classList.add('open');
+    });
+  });
 }
 
 function initFAQAccordion() {