diff --git a/index.html b/index.html
index 60fcbc9..f90ce20 100644
--- a/index.html
+++ b/index.html
@@ -252,6 +252,20 @@
     });
     for (var a of menu.querySelectorAll('a')) { a.addEventListener('click', closeMenu); }
   }
+  var nav = document.getElementById('nav');
+  var sections = Array.prototype.slice.call(document.querySelectorAll('[data-bg]'));
+  function updateNavTheme() {
+    var dark = false;
+    for (var s of sections) {
+      var r = s.getBoundingClientRect();
+      if (r.top <= 30 && r.bottom > 30) { dark = (s.dataset.bg === 'dark'); break; }
+    }
+    nav.classList.toggle('on-dark', dark);
+    if (menu) menu.classList.toggle('on-dark', dark);
+  }
+  updateNavTheme();
+  window.addEventListener('scroll', function () { window.requestAnimationFrame(updateNavTheme); }, { passive: true });
+  window.addEventListener('resize', updateNavTheme);
 })();
 </script>
 
diff --git a/style.css b/style.css
index 7dd5d6f..46eea09 100644
--- a/style.css
+++ b/style.css
@@ -95,6 +95,17 @@ a.tel { text-decoration: none; }
 .nav-mobile-menu .nav-cta { color: #fff !important; }
 @keyframes navFadeIn { from { opacity: 0; transform: translateY(-6px); } to { opacity: 1; transform: translateY(0); } }
 
+/* Adaptive: over a dark section, flip nav + menu to dark frosted with light text */
+.nav.on-dark { background: rgba(15, 23, 41, 0.5); border-bottom-color: rgba(247, 244, 239, 0.14); }
+.nav.on-dark .nav-links-desktop a { color: rgba(247, 244, 239, 0.85); }
+.nav.on-dark .nav-links-desktop a:hover { color: #fff; }
+.nav.on-dark .nav-logo-img { filter: brightness(0) invert(1); }
+.nav.on-dark .nav-toggle-icon .bar, .nav.on-dark .nav-toggle-icon .o-ring { stroke: #f7f4ef; }
+.nav-mobile-menu.on-dark { background: rgba(15, 23, 41, 0.55); border-bottom-color: rgba(247, 244, 239, 0.14); }
+.nav-mobile-menu.on-dark a { color: rgba(247, 244, 239, 0.9); }
+.nav-mobile-menu.on-dark a:hover { color: #fff; }
+.nav-mobile-menu.on-dark .nav-cta { color: #fff !important; }
+
 @media (max-width: 900px) {
   .nav { padding: 0.7rem 1.5rem; }
   .nav-links-desktop { display: none; }