Smooth mobile nav transitions behind hamburger overlay

Instantly swap sections behind the menu overlay by temporarily
disabling CSS transitions, then fade out the menu to reveal the
new section already in place. Eliminates the flash of the previous
section during navigation.

Author: sin4ch

index.html

@@ -2142,13 +2142,20 @@
     navItems.forEach(item => {
       item.addEventListener('click', () => {
         const targetId = item.dataset.target;
-        showSection(targetId);
-        // Close hamburger menu on mobile after nav click
         if (sidebar.classList.contains('menu-open')) {
+          // Disable section transitions so the swap is instant behind the overlay
+          sections.forEach(s => s.style.transition = 'none');
+          showSection(targetId);
+          // Force reflow so the instant swap applies before re-enabling transitions
+          document.body.offsetHeight;
+          sections.forEach(s => s.style.transition = '');
+          // Now fade out the menu to reveal the new section already in place
           sidebar.classList.remove('menu-open');
           hamburger.classList.remove('open');
           document.body.style.overflow = '';
           if (carouselWrapperEl) carouselWrapperEl.style.display = '';
+        } else {
+          showSection(targetId);
         }
       });
     });