diff --git a/AI_INIT.md b/AI_INIT.md
index 3580528..85c3323 100644
--- a/AI_INIT.md
+++ b/AI_INIT.md
@@ -98,6 +98,7 @@ The following features are critical and must not be removed or fundamentally alt
 > [!CAUTION]
 > **AI AGENTS MUST FOLLOW THIS EXACT SEQUENCE WHEN RELEASING A NEW VERSION OR TAGGING.**
 > The CI pipeline automatically injects the version from the git tag into `manifest.base.json`, `shared/constants.js`, and `package.json`. You do NOT need to manually bump version numbers.
+> - **Website Versioning**: **NEVER** manually modify the version fallback strings in `website/index.html`. The website dynamically fetches the latest version and release date from `website/version.json` at runtime using `website/app.js`. Manual bumps in the HTML file are completely redundant and should be avoided.
 1. **MANDATORY SYNTAX CHECK**: Before staging, committing, or pushing any changes, you **MUST** run a syntax validation check using `node -c` on every single modified JavaScript file (e.g., `node -c extension/background.js` and `node -c extension/content.js`). **NEVER** commit or push code that fails this check.
 2. Commit all verified code changes and push to `main`.
 3. Create and push a new tag. **MANDATORY**: Tags MUST start with a `v` (e.g., `v1.4.0`). The GitHub Actions release workflow is strictly configured to ignore any tags without the `v` prefix.
diff --git a/website/app.js b/website/app.js
index b9d3fdf..f34abc2 100644
--- a/website/app.js
+++ b/website/app.js
@@ -71,11 +71,26 @@ document.addEventListener('DOMContentLoaded', () => {
                         
                         if (actions) {
                             if (!isInstalled) {
-                                actions.innerHTML = `
-                                    <a href="#" class="primary" style="text-align:center; text-decoration:none; display:block; padding: 1.2rem; background: var(--accent); color: white; border-radius: 12px; font-weight: 700;">GET IT ON CHROME WEBSTORE</a>
-                                    <a href="https://github.com/shik3i/KoalaSync" style="text-align:center; color:var(--accent); text-decoration:underline; font-size:0.85rem; margin-top:0.8rem; display:block; font-weight: 600;">Download via GitHub</a>
-                                    <p style="text-align:center; font-size:0.8rem; opacity:0.7; margin-top: 1.2rem; color: var(--text-muted);">The extension is required to join and sync videos.</p>
-                                `;
+                                const isFirefox = navigator.userAgent.includes('Firefox');
+                                if (isFirefox) {
+                                    actions.innerHTML = `
+                                        <a href="https://addons.mozilla.org/de/firefox/addon/koalasync/" class="primary btn-firefox" style="text-align:center; text-decoration:none; display:block; padding: 1.2rem; border-radius: 12px; font-weight: 700;">GET IT ON MOZILLA ADD-ONS</a>
+                                        <a href="https://github.com/shik3i/KoalaSync" style="text-align:center; color:#e66000; text-decoration:underline; font-size:0.85rem; margin-top:0.8rem; display:block; font-weight: 600;">Download via GitHub</a>
+                                        <p style="text-align:center; font-size:0.8rem; opacity:0.7; margin-top: 1.2rem; color: var(--text-muted);">
+                                            <span lang="en">The extension is required to join and sync videos.</span>
+                                            <span lang="de">Die Erweiterung ist erforderlich, um beizutreten und Videos zu synchronisieren.</span>
+                                        </p>
+                                    `;
+                                } else {
+                                    actions.innerHTML = `
+                                        <a href="#" class="primary" style="text-align:center; text-decoration:none; display:block; padding: 1.2rem; background: var(--accent); color: white; border-radius: 12px; font-weight: 700;">GET IT ON CHROME WEBSTORE</a>
+                                        <a href="https://github.com/shik3i/KoalaSync" style="text-align:center; color:var(--accent); text-decoration:underline; font-size:0.85rem; margin-top:0.8rem; display:block; font-weight: 600;">Download via GitHub</a>
+                                        <p style="text-align:center; font-size:0.8rem; opacity:0.7; margin-top: 1.2rem; color: var(--text-muted);">
+                                            <span lang="en">The extension is required to join and sync videos.</span>
+                                            <span lang="de">Die Erweiterung ist erforderlich, um beizutreten und Videos zu synchronisieren.</span>
+                                        </p>
+                                    `;
+                                }
                             } else {
                                 actions.innerHTML = `
                                     <div class="joining-spinner" style="text-align:center; padding: 1rem;">
diff --git a/website/index.html b/website/index.html
index c415456..900d904 100644
--- a/website/index.html
+++ b/website/index.html
@@ -4,7 +4,7 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>KoalaSync | Real-time Video Synchronization for Friends</title>
-    <meta name="description" content="Watch YouTube, Twitch, and HTML5 videos perfectly synchronized with friends. KoalaSync is a privacy-first, open-source Chrome extension.">
+    <meta name="description" content="Watch YouTube, Twitch, and HTML5 videos perfectly synchronized with friends. KoalaSync is a privacy-first, open-source browser extension for Chrome and Firefox.">
     
     <link rel="stylesheet" href="style.css">
     <link rel="icon" type="image/png" href="assets/logo.png">
@@ -65,7 +65,7 @@
     <header class="hero">
         <div class="container hero-grid">
             <div class="hero-text">
-                <div class="version-badge" data-reveal><span lang="en" class="version-text-en">v1.3.1 OUT NOW</span><span lang="de" class="version-text-de">v1.3.1 JETZT VERFÜGBAR</span></div>
+                <div class="version-badge" data-reveal><span lang="en" class="version-text-en">v1.5.3 OUT NOW</span><span lang="de" class="version-text-de">v1.5.3 JETZT VERFÜGBAR</span></div>
                 <h1 data-reveal>
                     <span lang="en">Watch Together.<br>Sync Perfectly.</span>
                     <span lang="de">Gemeinsam schauen.<br>Perfekt synchron.</span>
@@ -76,10 +76,10 @@
                 </h2>
                 <div class="cta-group" data-reveal>
                     <a href="#" class="btn btn-primary">
-                        <img src="assets/chrome.svg" width="20" style="filter: brightness(100)">
+                        <img src="assets/chrome.svg" width="20">
                         <span lang="en">Add to Chrome</span><span lang="de">Zu Chrome hinzufügen</span>
                     </a>
-                    <a href="#" class="btn btn-primary" style="background: #e66000;">
+                    <a href="https://addons.mozilla.org/de/firefox/addon/koalasync/" class="btn btn-firefox">
                         🦊
                         <span lang="en">Add to Firefox</span><span lang="de">Zu Firefox hinzufügen</span>
                     </a>
@@ -110,8 +110,8 @@
                 <div class="feature-card" data-reveal>
                     <div class="feature-icon">🎬</div>
                     <h3><span lang="en">Episode Auto-Sync</span><span lang="de">Automatische Episoden-Synchronisation</span></h3>
-                    <p lang="en">New in v1.3.1: Perfectly sync series binges. All peers wait until everyone has loaded the next episode.</p>
-                    <p lang="de">Neu in v1.3.1: Perfekt synchronisiertes Serien-Bingeing. Alle warten, bis jeder die nächste Episode geladen hat.</p>
+                    <p lang="en">Perfectly sync series binges. All peers wait until everyone has loaded the next episode.</p>
+                    <p lang="de">Perfekt synchronisiertes Serien-Bingeing. Alle warten, bis jeder die nächste Episode geladen hat.</p>
                 </div>
                 <div class="feature-card" data-reveal>
                     <div class="feature-icon">🛡️</div>
@@ -141,8 +141,8 @@
                     <div class="step-text" data-reveal>
                         <div class="step-num">01</div>
                         <h3><span lang="en">Install Extension</span><span lang="de">Erweiterung installieren</span></h3>
-                        <p lang="en">Add KoalaSync to your browser from the Chrome Web Store or download the latest developer ZIP from GitHub.</p>
-                        <p lang="de">Fügen Sie KoalaSync aus dem Chrome Web Store zu Ihrem Browser hinzu oder laden Sie die neueste Entwickler-ZIP von GitHub herunter.</p>
+                        <p lang="en">Add KoalaSync to your browser from the Chrome Web Store, Firefox Add-ons, or download the latest developer ZIP from GitHub.</p>
+                        <p lang="de">Füge KoalaSync aus dem Chrome Web Store, den Firefox Add-ons oder über die Entwickler-ZIP von GitHub zu deinem Browser hinzu.</p>
                     </div>
                     <div style="background: var(--card); height: 200px; border-radius: 20px; border: 1px solid var(--glass-border);"></div>
                 </div>
diff --git a/website/join.html b/website/join.html
index c258ed7..dc1fb4a 100644
--- a/website/join.html
+++ b/website/join.html
@@ -77,10 +77,11 @@
     <footer>
         <div class="container">
             <p>&copy; 2026 KoalaSync. Open source under the MIT License.</p>
-            <p style="font-size: 0.8rem; margin-top: 0.5rem;">No data is stored on our servers. Pure RAM-based relay.</p>
+            <p lang="en" style="font-size: 0.8rem; margin-top: 0.5rem;">No data is stored on our servers. Pure RAM-based relay.</p>
+            <p lang="de" style="font-size: 0.8rem; margin-top: 0.5rem;">Keine Daten werden auf unseren Servern gespeichert. Reines RAM-basiertes Relay.</p>
             <div style="margin-top: 1.5rem; font-size: 0.8rem; display: flex; justify-content: center; gap: 1.5rem;">
-                <a href="impressum.html" style="color: var(--text-muted); text-decoration: none;">Impressum</a>
-                <a href="datenschutz.html" style="color: var(--text-muted); text-decoration: none;">Datenschutz</a>
+                <a href="impressum.html" style="color: var(--text-muted); text-decoration: none;"><span lang="en">Legal Notice</span><span lang="de">Impressum</span></a>
+                <a href="datenschutz.html" style="color: var(--text-muted); text-decoration: none;"><span lang="en">Privacy Policy</span><span lang="de">Datenschutz</span></a>
             </div>
         </div>
     </footer>
diff --git a/website/style.css b/website/style.css
index e497d10..053d0b8 100644
--- a/website/style.css
+++ b/website/style.css
@@ -213,6 +213,18 @@ nav {
     box-shadow: 0 20px 25px -5px var(--accent-glow);
 }
 
+.btn-firefox {
+    background: #e66000;
+    color: white;
+    box-shadow: 0 10px 15px -3px rgba(230, 96, 0, 0.3);
+}
+
+.btn-firefox:hover {
+    background: #ff7300;
+    transform: translateY(-2px);
+    box-shadow: 0 20px 25px -5px rgba(230, 96, 0, 0.4);
+}
+
 .btn-secondary {
     background: var(--card);
     color: var(--text);