diff --git a/css/navigation.css b/css/navigation.css
index 3e078a6..fbd21af 100644
--- a/css/navigation.css
+++ b/css/navigation.css
@@ -1,22 +1,29 @@
-/* Shahnam und Vincent: Gemeinsame Kopfzeile für US 04-05. */
+/* Shahnam und Vincent: Gemeinsame Navigation für US 04-05. */
 :root {
     --navigation-height: 99px;
+    scroll-padding-top: calc(var(--navigation-offset, var(--navigation-height)) + 16px);
 }
-.site-navigation {
-/* Werte per Pixel-Sampling aus dem Referenz-Screenshot (Produktübersicht) übernommen */
-    --background: #071419; /* früher "bg-dark */
-    --background-rgb: 7 20 25;  /* gleiche Basisfarbe wie --background, 
-    aber ohne fixes Alpha – für Gradient-Stops 
-    wird benutzt um Bildern einen gradient zu verpassen */
-    --background-panel: #152027; /* früher "primary */
-    --accent: #4597A3;
-    --accent-soft: rgba(69, 151, 163, 0.14);
-    --text-primary: #ffffff;
-    --text-muted: #7e858a;
-    --text-muted2: #b7bec2;
 
-    --font-display: "Sora", "Inter", system-ui, sans-serif;
-    --font-body: "Inter", system-ui, sans-serif;
+.site-navigation {
+    color-scheme: dark;
+    --background: #071419;
+    --background-panel: #152027;
+    --accent: #4597a3;
+    --accent-soft: rgb(69 151 163 / 14%);
+    --text-primary: #fff;
+    --text-muted: #b7bec2;
+    --border: rgb(255 255 255 / 16%);
+
+    /* Bleibt beim Scrollen sichtbar und behält ihren Platz im Layout. */
+    position: sticky;
+    top: 0;
+    z-index: 100;
+    border-top: 3px solid var(--background);
+    background: var(--background);
+    color: var(--text-primary);
+    font-family: system-ui, -apple-system, "Segoe UI", Arial, sans-serif;
+    line-height: 1.6;
+    box-shadow: 0 4px 16px rgb(0 0 0 / 16%);
 }
 
 .site-navigation,
@@ -24,18 +31,6 @@
     box-sizing: border-box;
 }
 
-.site-navigation {
-    /* Bleibt über alle Seitenbereiche hinweg oben sichtbar und behält ihren Platz im Layout. */
-    position: sticky;
-    top: 0;
-    z-index: 100;
-    border-top: 3px solid var(--accent);
-    background: var(--background);
-    color: var(--text-primary);
-    font-family: system-ui, -apple-system, "Segoe UI", Arial, sans-serif;
-    line-height: 1.6;
-    box-shadow: 0 4px 16px rgb(0 0 0 / 16%);
-}
 .site-navigation__bar {
     display: flex;
     align-items: center;
@@ -44,13 +39,13 @@
     width: min(1680px, calc(100% - clamp(40px, 10vw, 192px)));
     margin-inline: auto;
 }
+
 .site-navigation .brand {
     display: flex;
     align-items: center;
     gap: 20px;
-    width: min(1680px, calc(100% - clamp(40px, 10vw, 192px)));
+    min-width: 0;
     min-height: calc(var(--navigation-height) - 3px);
-    margin-inline: auto;
     padding-block: 8px;
 }
 
@@ -62,26 +57,34 @@
     padding: 0;
     list-style: none;
 }
- 
-.site-navigation__links a {
+
+.site-navigation__links a,
+.site-navigation .navigation-disabled {
+    display: block;
+    padding-block: 10px;
     color: var(--text-muted);
     font-size: 15px;
     font-weight: 600;
     text-decoration: none;
-    transition: color 0.15s ease;
+    white-space: nowrap;
 }
- 
+
 .site-navigation__links a:hover,
 .site-navigation__links a:focus-visible {
     color: var(--text-primary);
 }
- 
-.site-navigation__links a:focus-visible {
+
+.site-navigation__links a:focus-visible,
+.site-navigation .menu-toggle:focus-visible {
     outline: 2px solid var(--accent);
     outline-offset: 4px;
     border-radius: 4px;
 }
- 
+
+.site-navigation .navigation-disabled {
+    opacity: 0.5;
+    cursor: default;
+}
 
 .site-navigation .brand__logo {
     display: grid;
@@ -90,6 +93,7 @@
     width: 60px;
     height: 60px;
     border-radius: 22px;
+    overflow: hidden;
     background: var(--text-primary);
 }
 
@@ -98,6 +102,12 @@
     width: 60px;
     height: 60px;
     object-fit: contain;
+    border-radius: inherit;
+}
+
+.site-navigation .brand__logo:focus-visible {
+    outline: 2px solid var(--accent);
+    outline-offset: 4px;
 }
 
 .site-navigation .brand__text {
@@ -116,17 +126,101 @@
 }
 
 .site-navigation .brand__label {
-    color: var(--text-muted2); 
+    color: var(--text-muted);
     font-size: 17px;
     font-weight: 600;
     line-height: 1.4;
 }
 
+.site-navigation .menu-toggle {
+    display: none;
+    flex-shrink: 0;
+    align-items: center;
+    justify-content: center;
+    width: 44px;
+    height: 44px;
+    padding: 0;
+    border: 1px solid var(--border);
+    border-radius: 10px;
+    background: transparent;
+    color: var(--text-primary);
+    font: inherit;
+    font-size: 26px;
+    line-height: 1;
+    cursor: pointer;
+}
+
+.site-navigation .menu-toggle:hover {
+    background: var(--accent-soft);
+}
+
+.site-navigation__backdrop {
+    display: none;
+}
+
+/* Der gleiche Grenzwert wird in navigation.js verwendet. */
+@media (max-width: 1100px) {
+    .site-navigation .menu-toggle {
+        display: inline-flex;
+    }
+
+    .site-navigation__links {
+        display: none;
+        position: absolute;
+        z-index: 2;
+        top: 100%;
+        right: 0;
+        width: min(360px, 100%);
+        max-height: calc(100vh - var(--navigation-offset, var(--navigation-height)));
+        max-height: calc(100dvh - var(--navigation-offset, var(--navigation-height)));
+        overflow-y: auto;
+        overscroll-behavior: contain;
+        padding: 16px 24px 24px;
+        border: 1px solid var(--border);
+        border-top: 0;
+        border-radius: 0 0 0 16px;
+        background: var(--background);
+        box-shadow: -8px 12px 24px rgb(0 0 0 / 20%);
+    }
+
+    .site-navigation__links ul {
+        align-items: stretch;
+        flex-direction: column;
+        gap: 4px;
+    }
+
+    .site-navigation__links a,
+    .site-navigation .navigation-disabled {
+        padding: 12px 16px;
+        border-radius: 8px;
+    }
+
+    .site-navigation__links a:hover {
+        background: var(--accent-soft);
+    }
+
+    .site-navigation.is-open .site-navigation__links,
+    .site-navigation.is-open .site-navigation__backdrop {
+        display: block;
+    }
+
+    .site-navigation__backdrop {
+        position: fixed;
+        z-index: 1;
+        inset: var(--navigation-offset, var(--navigation-height)) 0 0;
+        background: rgb(0 0 0 / 45%);
+    }
+}
+
 @media (max-width: 700px) {
     :root {
         --navigation-height: 81px;
     }
 
+    .site-navigation__bar {
+        gap: 12px;
+    }
+
     .site-navigation .brand {
         gap: 12px;
     }
diff --git a/images/contact-support-trihub.png b/images/contact-support-trihub.png
new file mode 100644
index 0000000..3efa1da
Binary files /dev/null and b/images/contact-support-trihub.png differ
diff --git a/index.html b/index.html
index 6a4b692..c0e6deb 100644
--- a/index.html
+++ b/index.html
@@ -16,6 +16,7 @@
     <link rel="stylesheet" href="css/leistungen.css">
     <link rel="stylesheet" href="css/berater.css">
     <link rel="stylesheet" href="css/beratung.css">
+    <script src="js/navigation.js" defer></script>
     <script src="js/leistungen.js" defer></script>
     <script src="js/berater.js" defer></script>
     <script src="js/beratung.js" defer></script>
@@ -26,24 +27,27 @@
     <header class="site-navigation">
         <div class="site-navigation__bar">
             <div class="brand">
-                <div class="brand__logo">
+                <a class="brand__logo" href="https://tri-hub.de/" aria-label="Zur Trihub-Startseite">
                     <img src="images/trihub-logo.jpg" alt="Trihub – fit und vital ab 50!" width="500" height="500">
-                </div>
+                </a>
                 <div class="brand__text">
                     <span class="brand__name">TRI-HUB</span>
                     <span class="brand__label">Triathlon als sportliches Zuhause ab 50</span>
                 </div>
             </div>
-            <nav class="site-navigation__links" aria-label="Hauptnavigation">
+            <button class="menu-toggle" type="button" aria-controls="navigation-links"
+                aria-expanded="false" aria-label="Menü öffnen">☰</button>
+            <nav class="site-navigation__links" id="navigation-links" aria-label="Hauptnavigation">
                 <ul>
                     <li><a href="#produktuebersicht">Übersicht</a></li>
                     <li><a href="#leistungen">Pakete</a></li>
                     <li><a href="#berater">Berater</a></li>
                     <li><a href="#beratung">Infos</a></li>
-                    <li><a href="#kontakt">Kontakt</a></li>
+                    <li><span class="navigation-disabled" aria-disabled="true">Kontakt</span></li>
                 </ul>
             </nav>
         </div>
+        <div class="site-navigation__backdrop" aria-hidden="true"></div>
     </header>
 
     <main id="main-content">
diff --git a/js/navigation.js b/js/navigation.js
new file mode 100644
index 0000000..1a0f202
--- /dev/null
+++ b/js/navigation.js
@@ -0,0 +1,73 @@
+(() => {
+    const navigation = document.querySelector('.site-navigation');
+    if (!navigation) return;
+
+    const button = navigation.querySelector('.menu-toggle');
+    const links = navigation.querySelector('#navigation-links');
+    const backdrop = navigation.querySelector('.site-navigation__backdrop');
+    if (!button || !links || !backdrop) return;
+
+    // Muss zum Grenzwert in navigation.css passen.
+    const mobileView = window.matchMedia('(max-width: 1100px)');
+
+    function setMenuOpen(isOpen) {
+        isOpen = isOpen && mobileView.matches;
+        navigation.classList.toggle('is-open', isOpen);
+        button.setAttribute('aria-expanded', String(isOpen));
+        button.setAttribute('aria-label', isOpen ? 'Menü schließen' : 'Menü öffnen');
+        button.textContent = isOpen ? '✕' : '☰';
+    }
+
+    button.addEventListener('click', () => {
+        setMenuOpen(button.getAttribute('aria-expanded') !== 'true');
+    });
+
+    // Nach einem Sprung bleibt der Tastaturfokus im gewählten Bereich.
+    links.addEventListener('click', (event) => {
+        const link = event.target.closest('a');
+        if (!link || !mobileView.matches) return;
+        setMenuOpen(false);
+        const target = document.querySelector(link.getAttribute('href'));
+        if (target) {
+            const hadTabindex = target.hasAttribute('tabindex');
+            if (!hadTabindex) target.setAttribute('tabindex', '-1');
+            requestAnimationFrame(() => target.focus({ preventScroll: true }));
+            if (!hadTabindex) {
+                target.addEventListener('blur', () => target.removeAttribute('tabindex'), { once: true });
+            }
+        }
+    });
+
+    document.addEventListener('keydown', (event) => {
+        if (event.key === 'Escape' && button.getAttribute('aria-expanded') === 'true') {
+            setMenuOpen(false);
+            button.focus();
+        }
+    });
+
+    backdrop.addEventListener('click', () => {
+        setMenuOpen(false);
+        button.focus();
+    });
+
+    // Das Menü bleibt beim Weitergehen mit Tab nicht über dem Seiteninhalt liegen.
+    navigation.addEventListener('focusout', (event) => {
+        if (!navigation.contains(event.relatedTarget)) setMenuOpen(false);
+    });
+
+    mobileView.addEventListener('change', () => {
+        const focusedElement = document.activeElement;
+        setMenuOpen(false);
+        if (mobileView.matches && links.contains(focusedElement)) button.focus();
+        if (!mobileView.matches && focusedElement === button) links.querySelector('a')?.focus();
+    });
+
+    // Berücksichtigt auch umgebrochene Texte und vergrößerte Schrift.
+    const headerObserver = new ResizeObserver(() => {
+        document.documentElement.style.setProperty(
+            '--navigation-offset', `${navigation.getBoundingClientRect().height}px`
+        );
+    });
+    headerObserver.observe(navigation);
+    setMenuOpen(false);
+})();