diff --git a/program/Index.html b/program/Index.html
new file mode 100644
index 0000000..02c25a8
--- /dev/null
+++ b/program/Index.html
@@ -0,0 +1,157 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Bibliotheks-Hub</title>
+    <link rel="stylesheet" href="style.css">
+</head>
+<body>
+
+    <div id="auth-section" class="auth-modal hidden">
+        <div class="auth-container">
+            <div id="login-form" class="auth-form">
+                <div class="auth-box">
+                    <h1>Bibliotheks-Hub</h1>
+                    <p>Digitale Bibliotheksverwaltung</p>
+                    <input type="text" id="login-username" placeholder="Benutzername" class="input-field">
+                    <input type="password" id="login-password" placeholder="Passwort" class="input-field">
+                    <button onclick="handleLogin()" class="btn-primary">Anmelden</button>
+                    <p class="toggle-link">Neu hier? <a href="#" onclick="toggleAuthForm()">Konto erstellen</a></p>
+                </div>
+            </div>  
+
+            <div id="register-form" class="auth-form hidden">
+                <div class="auth-box">
+                    <h1>Bibliotheks-Hub</h1>
+                    <p>Erstelle dein Konto</p>
+                    <input type="text" id="register-username" placeholder="Benutzername" class="input-field">
+                    <input type="email" id="register-email" placeholder="E-Mail" class="input-field">
+                    <input type="password" id="register-password" placeholder="Passwort" class="input-field">
+                    <input type="text" id="register-fullname" placeholder="Vollständiger Name" class="input-field">
+                    <button onclick="handleRegister()" class="btn-primary">Konto erstellen</button>
+                    <p class="toggle-link">Bereits ein Konto? <a href="#" onclick="toggleAuthForm()">Anmelden</a></p>
+                </div>
+            </div>
+        </div>
+    </div>
+
+    <!-- Main App -->
+    <div id="app-section">
+        <!-- Sidebar -->
+        <aside class="sidebar">
+            <div class="sidebar-header">
+                <h2>Library</h2>
+            </div>
+     <nav class="sidebar-nav">
+
+        <button onclick="switchTab('dashboard')" class="nav-item active" id="tab-dashboard">
+        Startseite
+        </button>
+
+        <button onclick="switchTab('books')" class="nav-item" id="tab-books">
+        Durchsuchen
+        </button>
+
+        <button onclick="switchTab('my-books')" class="nav-item" id="tab-my-books">
+        Meine Bücher
+        </button>
+
+        <button onclick="switchTab('history')" class="nav-item" id="tab-history">
+        Verlauf
+        </button>
+
+        <button onclick="switchTab('admin')" class="nav-item" id="tab-admin" style="display:none;">
+        Verwaltung
+        </button>
+
+        </nav>
+            <div class="sidebar-footer">
+                <p id="welcome-sidebar"></p>
+                <button onclick="logout()" class="btn-logout">Abmelden</button>
+            </div>
+        </aside>
+
+        <!-- Main Content -->
+        <main class="main-content">
+            <!-- Dashboard Tab -->
+            <div id="dashboard-tab" class="tab-content">
+                <div class="page-header">
+                    <h1>Neuigkeiten</h1>
+                </div>
+                <div id="news-container" class="news-grid"></div>
+            </div>
+
+            <!-- Browse Books Tab -->
+            <div id="books-tab" class="tab-content hidden">
+                <div class="page-header">
+                    <h1>Bücher durchsuchen</h1>
+                </div>
+                <div class="search-bar">
+                    <input type="text" id="search-books" placeholder="Bücher suchen..." class="input-field" onkeyup="renderBooks()">
+                    <select id="filter-status" class="select-field" onchange="renderBooks()">
+                        <option value="all">Alle</option>
+                        <option value="available">Verfügbar</option>
+                        <option value="borrowed">Ausgeliehen</option>
+                    </select>
+                    <select id="filter-genre" class="select-field" onchange="renderBooks()">
+                        <option value="">Alle Genres</option>
+                    </select>
+                </div>
+                <div id="book-list" class="books-container"></div>
+            </div>
+
+            <!-- My Books Tab -->
+            <div id="my-books-tab" class="tab-content hidden">
+                <div class="page-header">
+                    <h1>Meine ausgeliehenen Bücher</h1>
+                </div>
+                <div id="borrow-timer">
+                    <div id="timer-text">Nächste Fälligkeit: --</div>
+                    <div class="timer-bar">
+                        <div id="timer-progress"></div>
+                    </div>
+                </div>
+                <div id="my-books-list" class="books-container"></div>
+            </div>
+
+            <!-- History Tab -->
+            <div id="history-tab" class="tab-content hidden">
+                <div class="page-header">
+                    <h1>Ausleihverlauf</h1>
+                </div>
+                <div style="display: flex; flex-wrap: wrap; gap: 12px; align-items: center; margin-bottom: 15px;">
+                    <select id="history-filter" class="select-field" onchange="renderHistory()">
+                        <option value="all">Alle</option>
+                        <option value="returned">Zurückgegeben</option>
+                        <option value="borrowed">Aktuell ausgeliehen</option>
+                    </select>
+                    <button onclick="clearHistory()" class="btn-clear">Verlauf löschen</button>
+                </div>
+                <div id="history-list" class="history-container"></div>
+            </div>
+
+            <!-- Admin Tab -->
+            <div id="admin-tab" class="tab-content hidden">
+                <div class="page-header">
+                    <h1>Admin-Bereich</h1>
+                </div>
+                <div class="admin-section">
+                    <h2>Neues Buch hinzufügen</h2>
+                    <div class="form-grid">
+                        <input type="text" id="admin-title" placeholder="Titel" class="input-field">
+                        <input type="text" id="admin-author" placeholder="Autor" class="input-field">
+                        <input type="text" id="admin-genre" placeholder="Genre" class="input-field">
+                        <input type="number" id="admin-quantity" placeholder="Anzahl" class="input-field" value="1">
+                        <button onclick="addBookAdmin()" class="btn-primary">Buch hinzufügen</button>
+                    </div>
+                </div>
+                <h2 style="margin-top: 30px;">Alle Bücher</h2>
+                <div id="admin-book-list" class="books-container"></div>
+            </div>
+        </main>
+    </div>
+
+    <script src="script.js"></script>
+</body>
+</html>
\ No newline at end of file
diff --git a/program/Style.css b/program/Style.css
new file mode 100644
index 0000000..8331b8c
--- /dev/null
+++ b/program/Style.css
@@ -0,0 +1,670 @@
+* {
+    margin: 0;
+    padding: 0;
+    box-sizing: border-box;
+}
+
+body {
+    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
+    background: #f5f5f5;
+    color: #333;
+}
+
+/* Auth Section Modal */
+.auth-modal {
+    position: fixed;
+    top: 0;
+    left: 0;
+    right: 0;
+    bottom: 0;
+    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    z-index: 9999;
+}
+
+.auth-modal.hidden {
+    display: none !important;
+}
+
+.auth-container {
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    padding: 20px;
+}
+
+.auth-form {
+    animation: fadeIn 0.3s ease;
+}
+
+.auth-form.hidden {
+    display: none;
+}
+
+.auth-box {
+    background: white;
+    padding: 50px 40px;
+    border-radius: 12px;
+    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
+    width: 100%;
+    max-width: 380px;
+}
+
+.auth-box h1 {
+    font-size: 32px;
+    margin-bottom: 8px;
+    color: #333;
+    text-align: center;
+}
+
+.auth-box p {
+    text-align: center;
+    color: #999;
+    margin-bottom: 30px;
+    font-size: 14px;
+}
+
+.input-field {
+    width: 100%;
+    padding: 12px 15px;
+    margin-bottom: 12px;
+    border: 1px solid #ddd;
+    border-radius: 6px;
+    font-size: 14px;
+    transition: all 0.3s;
+    font-family: inherit;
+}
+
+.input-field:focus {
+    outline: none;
+    border-color: #667eea;
+    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
+}
+
+.btn-primary {
+    width: 100%;
+    padding: 12px;
+    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
+    color: white;
+    border: none;
+    border-radius: 6px;
+    font-size: 15px;
+    font-weight: 600;
+    cursor: pointer;
+    transition: all 0.3s;
+    margin-top: 8px;
+    font-family: inherit;
+}
+
+.btn-primary:hover {
+    transform: translateY(-2px);
+    box-shadow: 0 10px 20px rgba(102, 126, 234, 0.3);
+}
+
+.toggle-link {
+    text-align: center;
+    margin-top: 20px;
+    color: #999;
+    font-size: 13px;
+}
+
+.toggle-link a {
+    color: #667eea;
+    text-decoration: none;
+    font-weight: 600;
+    cursor: pointer;
+}
+
+.toggle-link a:hover {
+    text-decoration: underline;
+}
+
+/* Main App Layout */
+#app-section {
+    display: flex;
+    min-height: 100vh;
+}
+
+.sidebar {
+    width: 250px;
+    background: white;
+    border-right: 1px solid #e0e0e0;
+    display: flex;
+    flex-direction: column;
+    position: fixed;
+    height: 100vh;
+    left: 0;
+    top: 0;
+}
+
+.sidebar-header {
+    padding: 25px 20px;
+    border-bottom: 1px solid #f0f0f0;
+}
+
+.sidebar-header h2 {
+    font-size: 24px;
+    color: #667eea;
+}
+
+.sidebar-nav {
+    flex: 1;
+    padding: 20px 0;
+    overflow-y: auto;
+}
+
+.nav-item {
+    width: 100%;
+    padding: 15px 20px;
+    background: none;
+    border: none;
+    text-align: left;
+    cursor: pointer;
+    color: #666;
+    font-size: 14px;
+    font-weight: 500;
+    transition: all 0.3s;
+    display: flex;
+    align-items: center;
+    gap: 12px;
+    font-family: inherit;
+}
+
+.nav-item:hover {
+    background: #f5f5f5;
+    color: #667eea;
+}
+
+.nav-item.active {
+    background: #f0f0ff;
+    color: #667eea;
+    border-right: 3px solid #667eea;
+}
+
+.icon {
+    font-size: 18px;
+}
+
+.sidebar-footer {
+    padding: 20px;
+    border-top: 1px solid #f0f0f0;
+}
+
+.sidebar-footer p {
+    font-size: 12px;
+    color: #999;
+    margin-bottom: 12px;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+}
+
+.btn-logout {
+    width: 100%;
+    padding: 10px;
+    background: #f5f5f5;
+    border: 1px solid #ddd;
+    border-radius: 6px;
+    cursor: pointer;
+    font-size: 13px;
+    font-weight: 600;
+    color: #666;
+    transition: all 0.3s;
+    font-family: inherit;
+}
+
+.btn-logout:hover {
+    background: #fff0f0;
+    border-color: #ff6b6b;
+    color: #ff6b6b;
+}
+
+.main-content {
+    flex: 1;
+    margin-left: 250px;
+    padding: 40px;
+    overflow-y: auto;
+}
+
+/* Content */
+.page-header {
+    margin-bottom: 30px;
+}
+
+.page-header h1 {
+    font-size: 32px;
+    color: #333;
+}
+
+.hidden {
+    display: none !important;
+}
+
+/* Dashboard */
+.stats-grid {
+    display: grid;
+    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
+    gap: 20px;
+    margin-bottom: 40px;
+}
+
+.stat-item {
+    background: white;
+    padding: 25px;
+    border-radius: 10px;
+    border-left: 4px solid #667eea;
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
+}
+
+.stat-item.alert {
+    border-left-color: #ff6b6b;
+}
+
+.stat-number {
+    font-size: 32px;
+    font-weight: 700;
+    color: #667eea;
+    margin-bottom: 5px;
+}
+
+.stat-item.alert .stat-number {
+    color: #ff6b6b;
+}
+
+.stat-label {
+    font-size: 13px;
+    color: #999;
+    font-weight: 500;
+}
+
+/*  News Grid */
+.news-grid {
+    display: grid;
+    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
+    gap: 20px;
+    margin-top: 20px;
+}
+
+.news-card {
+    background: white;
+    padding: 25px;
+    border-radius: 10px;
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
+    transition: transform 0.3s ease, box-shadow 0.3s ease;
+    border-left: 4px solid #667eea;
+}
+
+.news-card:hover {
+    transform: translateY(-5px);
+    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
+}
+
+.news-icon {
+    font-size: 36px;
+    margin-bottom: 15px;
+}
+
+.news-card h3 {
+    font-size: 18px;
+    color: #333;
+    margin-bottom: 8px;
+    font-weight: 600;
+}
+
+.news-subtitle {
+    font-size: 13px;
+    color: #667eea;
+    font-weight: 600;
+    margin-bottom: 10px;
+}
+
+.news-desc {
+    font-size: 14px;
+    color: #666;
+    line-height: 1.5;
+}
+
+.activity-section {
+    background: white;
+    padding: 25px;
+    border-radius: 10px;
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
+}
+
+.activity-section h3 {
+    font-size: 16px;
+    margin-bottom: 20px;
+    color: #333;
+}
+
+.activity-list {
+    display: flex;
+    flex-direction: column;
+    gap: 12px;
+}
+
+.activity-item {
+    padding: 12px 15px;
+    background: #f9f9f9;
+    border-radius: 6px;
+    font-size: 13px;
+    color: #666;
+    border-left: 3px solid #667eea;
+}
+
+/*  Search & Filters */
+.search-bar {
+    display: flex;
+    gap: 12px;
+    margin-bottom: 25px;
+    flex-wrap: wrap;
+}
+
+.search-bar .input-field {
+    flex: 1;
+    min-width: 200px;
+    margin-bottom: 0;
+}
+
+.select-field {
+    padding: 12px 12px;
+    border: 1px solid #ddd;
+    border-radius: 6px;
+    font-size: 13px;
+    background: white;
+    cursor: pointer;
+    transition: all 0.3s;
+    font-family: inherit;
+}
+
+.select-field:focus {
+    outline: none;
+    border-color: #667eea;
+}
+
+/* Books */
+.books-container {
+    display: grid;
+    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
+    gap: 20px;
+}
+
+.book-card {
+    background: white;
+    border-radius: 10px;
+    padding: 18px;
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
+    border: 1px solid #f0f0f0;
+    transition: all 0.3s;
+    display: flex;
+    flex-direction: column;
+}
+
+.book-card:hover {
+    transform: translateY(-4px);
+    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
+}
+
+.book-card.unavailable {
+    opacity: 0.7;
+}
+
+.book-card.overdue {
+    border-left: 4px solid #ff6b6b;
+}
+
+.book-card h3 {
+    font-size: 15px;
+    margin-bottom: 8px;
+    color: #333;
+    font-weight: 600;
+}
+
+.book-card p {
+    font-size: 12px;
+    color: #999;
+    margin-bottom: 8px;
+}
+
+.book-info {
+    margin-bottom: 12px;
+}
+
+.copies-badge {
+    display: inline-block;
+    background: #f0f0f0;
+    padding: 6px 10px;
+    border-radius: 4px;
+    font-size: 12px;
+    color: #666;
+    margin-bottom: 12px;
+    font-weight: 500;
+}
+
+.due-date {
+    font-size: 12px;
+    color: #667eea;
+    font-weight: 600;
+    margin-bottom: 12px;
+}
+
+.due-date.overdue {
+    color: #ff6b6b;
+    background: #fff0f0;
+    padding: 6px 10px;
+    border-radius: 4px;
+}
+
+.book-actions {
+    margin-top: auto;
+    display: flex;
+    gap: 8px;
+}
+
+.btn-borrow, .btn-return {
+    flex: 1;
+    padding: 10px;
+    border: none;
+    border-radius: 6px;
+    font-size: 12px;
+    font-weight: 600;
+    cursor: pointer;
+    transition: all 0.3s;
+    font-family: inherit;
+}
+
+.btn-borrow {
+    background: #667eea;
+    color: white;
+}
+
+.btn-borrow:hover {
+    background: #5568d3;
+}
+
+.btn-return {
+    background: #ff9500;
+    color: white;
+}
+
+.btn-return:hover {
+    background: #e68600;
+}
+
+.btn-clear {
+    padding: 10px 14px;
+    border: none;
+    border-radius: 6px;
+    font-size: 13px;
+    font-weight: 600;
+    cursor: pointer;
+    background: #ff6b6b;
+    color: white;
+    transition: all 0.3s;
+    font-family: inherit;
+}
+
+.btn-clear:hover {
+    background: #ff4a4a;
+}
+
+.empty-message {
+    text-align: center;
+    padding: 60px 20px;
+    color: #999;
+    font-size: 14px;
+}
+
+/*  History  */
+.history-container {
+    background: white;
+    border-radius: 10px;
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
+    overflow: hidden;
+    margin-top: 20px;
+}
+
+.history-table-content {
+    width: 100%;
+    border-collapse: collapse;
+}
+
+.history-table-content th {
+    background: #f5f5f5;
+    padding: 15px;
+    text-align: left;
+    font-size: 13px;
+    font-weight: 600;
+    color: #666;
+    border-bottom: 1px solid #e0e0e0;
+}
+
+.history-table-content td {
+    padding: 15px;
+    border-bottom: 1px solid #f0f0f0;
+    font-size: 13px;
+    color: #666;
+}
+
+.history-table-content tr:hover {
+    background: #f9f9f9;
+}
+
+/*  Admin  */
+.admin-section {
+    background: white;
+    padding: 25px;
+    border-radius: 10px;
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
+    margin-bottom: 30px;
+}
+
+.admin-section h2 {
+    font-size: 18px;
+    margin-bottom: 20px;
+    color: #333;
+}
+
+.form-grid {
+    display: grid;
+    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
+    gap: 12px;
+}
+
+.form-grid .btn-primary {
+    margin-top: 0;
+}
+
+/*  Animations  */
+@keyframes fadeIn {
+    from { opacity: 0; transform: translateY(10px); }
+    to { opacity: 1; transform: translateY(0); }
+}
+
+.tab-content {
+    animation: fadeIn 0.3s ease;
+}
+
+/*  Responsive  */
+@media (max-width: 768px) {
+    .sidebar {
+        width: 100%;
+        height: auto;
+        position: static;
+        border-right: none;
+        border-bottom: 1px solid #e0e0e0;
+    }
+
+    .sidebar-nav {
+        display: flex;
+        overflow-x: auto;
+        padding: 0;
+    }
+
+    .nav-item {
+        white-space: nowrap;
+        flex-shrink: 0;
+        padding: 12px 15px;
+        border-right: none;
+        border-bottom: 3px solid transparent;
+    }
+
+    .nav-item.active {
+        border-right: none;
+        border-bottom: 3px solid #667eea;
+    }
+
+    .sidebar-footer {
+        display: none;
+    }
+
+    .main-content {
+        margin-left: 0;
+        padding: 20px;
+    }
+
+    .stats-grid {
+        grid-template-columns: repeat(2, 1fr);
+    }
+
+    .books-container {
+        grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
+    }
+
+    .page-header h1 {
+        font-size: 24px;
+    }
+
+    .search-bar {
+        flex-direction: column;
+    }
+
+    .search-bar .select-field {
+        width: 100%;
+    }
+}
+
+@media (max-width: 480px) {
+    .auth-box {
+        padding: 30px 20px;
+    }
+
+    .auth-box h1 {
+        font-size: 24px;
+    }
+
+    .books-container {
+        grid-template-columns: 1fr;
+    }
+
+    .stats-grid {
+        grid-template-columns: 1fr;
+    }
+
+    .nav-item {
+        padding: 10px 12px;
+        font-size: 12px;
+    }
+}
\ No newline at end of file
diff --git a/program/script.js b/program/script.js
new file mode 100644
index 0000000..c761bbf
--- /dev/null
+++ b/program/script.js
@@ -0,0 +1,278 @@
+let user = null;
+const $ = id => document.getElementById(id);
+
+// DATA STORAGE
+const db = {
+    getUsers: () => JSON.parse(localStorage.getItem('users')) || [{ username: 'admin', email: 'admin@library.com', password: 'admin123', fullname: 'Administrator', isAdmin: true }],
+    saveUsers: u => localStorage.setItem('users', JSON.stringify(u)),
+    getBooks: () => JSON.parse(localStorage.getItem('books')) || [
+        { id: 1, title: 'To Kill a Mockingbird', author: 'Harper Lee', genre: 'Fiction', quantity: 3, borrowedBy: [] },
+        { id: 2, title: '1984', author: 'George Orwell', genre: 'Dystopian', quantity: 2, borrowedBy: [] },
+        { id: 3, title: 'Pride and Prejudice', author: 'Jane Austen', genre: 'Romance', quantity: 2, borrowedBy: [] },
+        { id: 4, title: 'The Great Gatsby', author: 'F. Scott Fitzgerald', genre: 'Classic', quantity: 3, borrowedBy: [] },
+        { id: 5, title: 'The Hobbit', author: 'J. R. R. Tolkien', genre: 'Fantasy', quantity: 2, borrowedBy: [] },
+        { id: 6, title: 'The Catcher in the Rye', author: 'J. D. Salinger', genre: 'Fiction', quantity: 2, borrowedBy: [] },
+        { id: 7, title: 'The Alchemist', author: 'Paulo Coelho', genre: 'Adventure', quantity: 2, borrowedBy: [] },
+        { id: 8, title: 'Harry Potter and the Sorcerer\'s Stone', author: 'J. K. Rowling', genre: 'Fantasy', quantity: 4, borrowedBy: [] },
+        { id: 9, title: 'The Lord of the Rings', author: 'J. R. R. Tolkien', genre: 'Fantasy', quantity: 2, borrowedBy: [] },
+        { id: 10, title: 'The Hunger Games', author: 'Suzanne Collins', genre: 'Dystopian', quantity: 3, borrowedBy: [] },
+        { id: 11, title: 'The Book Thief', author: 'Markus Zusak', genre: 'Historical Fiction', quantity: 2, borrowedBy: [] },
+        { id: 12, title: 'The Chronicles of Narnia', author: 'C. S. Lewis', genre: 'Fantasy', quantity: 2, borrowedBy: [] },
+        { id: 13, title: 'Brave New World', author: 'Aldous Huxley', genre: 'Dystopian', quantity: 2, borrowedBy: [] },
+        { id: 14, title: 'The Fault in Our Stars', author: 'John Green', genre: 'Romance', quantity: 3, borrowedBy: [] },
+        { id: 15, title: 'The Da Vinci Code', author: 'Dan Brown', genre: 'Mystery', quantity: 2, borrowedBy: [] },
+        { id: 16, title: 'The Shining', author: 'Stephen King', genre: 'Horror', quantity: 2, borrowedBy: [] },
+        { id: 17, title: 'The Girl with the Dragon Tattoo', author: 'Stieg Larsson', genre: 'Crime', quantity: 2, borrowedBy: [] },
+        { id: 18, title: 'Moby-Dick', author: 'Herman Melville', genre: 'Adventure', quantity: 1, borrowedBy: [] },
+        { id: 19, title: 'The Road', author: 'Cormac McCarthy', genre: 'Post-Apocalyptic', quantity: 2, borrowedBy: [] },
+        { id: 20, title: 'Jane Eyre', author: 'Charlotte Brontë', genre: 'Romance', quantity: 2, borrowedBy: [] }
+    ],
+    saveBooks: b => localStorage.setItem('books', JSON.stringify(b)),
+    getHistory: () => JSON.parse(localStorage.getItem('history')) || [],
+    saveHistory: h => localStorage.setItem('history', JSON.stringify(h))
+};
+
+// HELPERS
+const getUser = n => db.getUsers().find(u => u.username === n);
+const addHistory = (id, title, action, details) => {
+    const h = db.getHistory();
+    h.push({ id: Date.now(), username: user.username, bookId: id, bookTitle: title, action, timestamp: new Date().toISOString(), ...details });
+    db.saveHistory(h);
+};
+const getBorrowed = b => b.borrowedBy.filter(x => !x.returnDate).length;
+const getAvailable = b => b.quantity - getBorrowed(b);
+const formatDate = d => new Date(d).toLocaleDateString();
+const userRecord = (b, u) => b.borrowedBy.find(x => x.user === u && !x.returnDate);
+
+// INIT
+window.addEventListener('DOMContentLoaded', () => {
+    // Clear old data with ISBN and reset to new format with genres
+    const oldBooks = JSON.parse(localStorage.getItem('books') || '[]');
+    if (oldBooks.length > 0 && oldBooks[0].isbn) {
+        localStorage.removeItem('books');
+        localStorage.removeItem('history');
+    }
+    
+    user = localStorage.getItem('currentUser') ? getUser(localStorage.getItem('currentUser')) : { username: 'guest', fullname: 'Gast', isAdmin: false };
+    $('welcome-sidebar').innerText = user.fullname;
+    if (user.isAdmin) $('tab-admin').style.display = 'flex';
+    switchTab('dashboard');
+});
+
+// AUTHEN
+const handleRegister = () => {
+    const [u, e, p, f] = [$('register-username').value, $('register-email').value, $('register-password').value, $('register-fullname').value].map(x => x.trim());
+    if (!u || !e || !p || !f) return alert('Bitte alle Felder ausfüllen');
+    if (getUser(u)) return alert('Benutzer existiert bereits');
+    db.getUsers().push({ username: u, email: e, password: p, fullname: f, isAdmin: false, registeredDate: new Date().toISOString() });
+    db.saveUsers(db.getUsers());
+    alert('Erfolg! Du kannst dich jetzt anmelden.');
+    toggleAuthForm();
+    [$('register-username'), $('register-email'), $('register-password'), $('register-fullname')].forEach(x => x.value = '');
+};
+
+const handleLogin = () => {
+    const [u, p] = [$('login-username').value.trim(), $('login-password').value.trim()];
+    if (!u || !p) return alert('Bitte Anmeldedaten eingeben');
+    const userData = getUser(u);
+    if (!userData || userData.password !== p) return alert('Ungültige Anmeldedaten');
+    user = userData;
+    localStorage.setItem('currentUser', u);
+    $('login-username').value = '';
+    $('login-password').value = '';
+    $('auth-section').classList.add('hidden');
+    $('welcome-sidebar').innerText = user.fullname;
+    if (user.isAdmin) $('tab-admin').style.display = 'flex';
+    switchTab('dashboard');
+};
+
+const logout = () => {
+    localStorage.removeItem('currentUser');
+    user = { username: 'guest', fullname: 'Gast', isAdmin: false };
+    $('welcome-sidebar').innerText = 'Gast';
+    $('tab-admin').style.display = 'none';
+    $('auth-section').classList.remove('hidden');
+    switchTab('dashboard');
+};
+
+const toggleAuthForm = () => {
+    $('login-form').classList.toggle('hidden');
+    $('register-form').classList.toggle('hidden');
+};
+
+// BOOKS
+const borrowBook = bid => {
+    const books = db.getBooks();
+    const book = books.find(b => b.id === bid);
+    if (!book || userRecord(book, user.username) || getAvailable(book) <= 0) return alert('Kann nicht ausgeliehen werden');
+    const due = new Date();
+    due.setDate(due.getDate() + 14);
+    book.borrowedBy.push({ user: user.username, borrowDate: new Date().toISOString(), dueDate: due.toISOString(), returnDate: null });
+    db.saveBooks(books);
+    addHistory(book.id, book.title, 'BORROWED', { dueDate: due.toISOString() });
+    render();
+};
+
+const returnBook = bid => {
+    const books = db.getBooks();
+    const book = books.find(b => b.id === bid);
+    const record = userRecord(book, user.username);
+    if (!record) return alert('Nicht ausgeliehen');
+    record.returnDate = new Date().toISOString();
+    db.saveBooks(books);
+    addHistory(book.id, book.title, 'RETURNED');
+    render();
+};
+
+const addBookAdmin = () => {
+    const [t, a, g, q] = [$('admin-title').value.trim(), $('admin-author').value.trim(), $('admin-genre').value.trim(), parseInt($('admin-quantity').value) || 1];
+    if (!t || !a || !g) return alert('Bitte alle Felder ausfüllen');
+    const books = db.getBooks();
+    const existing = books.find(b => b.title === t);
+    if (existing) existing.quantity += q;
+    else books.push({ id: Date.now(), title: t, author: a, genre: g, quantity: q, borrowedBy: [] });
+    db.saveBooks(books);
+    [$('admin-title'), $('admin-author'), $('admin-genre'), $('admin-quantity')].forEach(x => x.value = x === $('admin-quantity') ? '1' : '');
+    renderAdminBooks();
+};
+
+// UI
+const switchTab = t => {
+    document.querySelectorAll('.tab-content').forEach(el => el.classList.add('hidden'));
+    document.querySelectorAll('.nav-item').forEach(el => el.classList.remove('active'));
+    $(t + '-tab').classList.remove('hidden');
+    $('tab-' + t).classList.add('active');
+    if (t === 'books') populateGenreFilter();
+    ({ books: renderBooks, 'my-books': renderMyBooks, history: renderHistory, admin: renderAdminBooks, dashboard: updateDashboard }[t] || (() => {}))();
+};
+
+const updateDashboard = () => {
+    const newsItems = [
+        { id: 1, title: 'Neuerscheinung: Die Mitternachtsbibliothek', subtitle: 'Matt Haig', desc: 'Eine fesselnde moderne Fantasy über die Entscheidungen, die wir nie getroffen haben. Jetzt verfügbar!' },
+        { id: 2, title: 'Autogrammstunde', subtitle: 'Brandon Sanderson Tour 2024', desc: 'Nimm teil an einer exklusiven Signierstunde mit Bestsellerautor Brandon Sanderson am 15. März um 18 Uhr.' },
+        { id: 3, title: 'Neuerscheinung', subtitle: 'Project Hail Mary - Andy Weir', desc: 'Erscheint am 28. Februar! Jetzt vorbestellen für dieses epische Sci-Fi-Abenteuer.' },
+        { id: 4, title: 'Neu im Bestand: Fourth Wing', subtitle: 'Rebecca Yarros', desc: 'Drachenreiter, Magie und epische Romantik. Diese Fantasy-Sensation jetzt in unserer Sammlung!' },
+        { id: 5, title: 'Autoren-Spotlight', subtitle: 'Colleen Hoover Kollektion', desc: 'Wir haben unseren Romance-Bereich um die vollständigen Werke von Colleen Hoover erweitert.' },
+        { id: 6, title: 'Lese-Challenge 2024', subtitle: 'Mach mit in der Community', desc: 'Lies 12 Bücher in diesem Jahr! Gewinne exklusive Lesezeichen und Bibliotheks-Preise.' },
+        { id: 7, title: 'Valentinstag-Special', subtitle: 'Romantische Bücher', desc: 'Entdecke unsere Auswahl an Liebesromanen und erhalte 20% Rabatt, wenn du 3 oder mehr ausleihst!' },
+        { id: 8, title: 'Beliebt jetzt', subtitle: 'Verity von Colleen Hoover', desc: 'Der meistgelesene Thriller, den Leser nicht aus der Hand legen können. Nur begrenzt verfügbar!' }
+    ];
+
+    const persistedIds = JSON.parse(localStorage.getItem('newsItemsOrder') || 'null');
+    const selectedIds = Array.isArray(persistedIds) && persistedIds.length ? persistedIds : newsItems.slice(0, 6).map(i => i.id);
+
+    if (!persistedIds) {
+        localStorage.setItem('newsItemsOrder', JSON.stringify(selectedIds));
+    }
+
+    const news = selectedIds.map(id => newsItems.find(i => i.id === id)).filter(Boolean);
+    $('news-container').innerHTML = news.map(n => `<div class="news-card"><h3>${n.title}</h3><p class="news-subtitle">${n.subtitle}</p><p class="news-desc">${n.desc}</p></div>`).join('');
+};
+
+const renderBooks = () => {
+    const books = db.getBooks();
+    const [s, st, g] = [$('search-books').value.toLowerCase(), $('filter-status').value, $('filter-genre').value];
+    const filtered = books.filter(b => (b.title.toLowerCase().includes(s) || b.author.toLowerCase().includes(s)) && (!g || b.genre === g) && (st === 'all' || (st === 'available' && getAvailable(b) > 0) || (st === 'borrowed' && getAvailable(b) === 0)));
+    $('book-list').innerHTML = filtered.map(b => {
+        const avail = getAvailable(b);
+        const rec = userRecord(b, user.username);
+        return `<div class="book-card ${avail > 0 ? 'available' : 'unavailable'}">
+            <h3>${b.title}</h3><p><strong>Autor:</strong> ${b.author}</p>
+            <p><strong>Genre:</strong> ${b.genre}</p><p class="copies-badge">Verfügbar: ${avail}/${b.quantity}</p>
+            <div class="book-actions">${rec ? `<p class="due-date ${new Date(rec.dueDate) < new Date() ? 'overdue' : ''}">Fällig: ${formatDate(rec.dueDate)}</p><button onclick="returnBook(${b.id})" class="btn-return">Zurückgeben</button>` : (avail > 0 ? `<button onclick="borrowBook(${b.id})" class="btn-borrow">Ausleihen</button>` : '')}</div>
+        </div>`;
+    }).join('');
+};
+
+const renderMyBooks = () => {
+    const books = db.getBooks().filter(b => userRecord(b, user.username)).map(b => ({ ...b, record: userRecord(b, user.username) }));
+    $('my-books-list').innerHTML = books.length === 0 ? '<p class="empty-message">Keine ausgeliehenen Bücher</p>' : books.map(b => {
+        const overdue = new Date(b.record.dueDate) < new Date();
+        return `<div class="book-card ${overdue ? 'overdue' : 'ontime'}">
+            <h3>${b.title}</h3><p><strong>Autor:</strong> ${b.author}</p>
+            <p><strong>Ausgeliehen:</strong> ${formatDate(b.record.borrowDate)}</p>
+            <p class="due-date ${overdue ? 'overdue' : ''}">Fällig: ${formatDate(b.record.dueDate)}</p>
+            ${overdue ? '<p style="background:red;color:white;padding:8px;border-radius:4px;font-weight:600;">ÜBERFÄLLIG</p>' : ''}
+            <button onclick="returnBook(${b.id})" class="btn-return">Zurückgeben</button>
+        </div>`;
+    }).join('');
+};
+
+const renderHistory = () => {
+    const hist = db.getHistory().filter(h => h.username === user.username);
+    const filtered = $('history-filter').value === 'all' ? hist : hist.filter(h => h.action === $('history-filter').value.toUpperCase());
+    $('history-list').innerHTML = filtered.length === 0 ? '<p class="empty-message">Kein Verlauf</p>' : 
+        `<table class="history-table-content"><tr><th>Datum</th><th>Titel</th><th>Aktion</th><th>Fällig</th></tr>${filtered.reverse().map(e => `<tr><td>${formatDate(e.timestamp)}</td><td>${e.bookTitle}</td><td>${e.action === 'BORROWED' ? 'Ausgeliehen' : 'Zurückgegeben'}</td><td>${e.dueDate ? formatDate(e.dueDate) : '-'}</td></tr>`).join('')}</table>`;
+};
+
+const clearHistory = () => {
+    if (!confirm('Verlauf löschen? Dies kann nicht rückgängig gemacht werden.')) return;
+    const updated = db.getHistory().filter(h => h.username !== user.username);
+    db.saveHistory(updated);
+    renderHistory();
+};
+
+const renderAdminBooks = () => {
+    const books = db.getBooks();
+    $('admin-book-list').innerHTML = books.map(b => {
+        const borrowed = getBorrowed(b);
+        const details = b.borrowedBy.filter(x => !x.returnDate).map(x => `<p>${x.user} (${formatDate(x.dueDate)}) ${new Date(x.dueDate) < new Date() ? 'ÜBERFÄLLIG' : ''}</p>`).join('');
+        return `<div class="book-card admin-card">
+            <h3>${b.title}</h3><p><strong>Autor:</strong> ${b.author}</p>
+            <p><strong>Genre:</strong> ${b.genre}</p><p><strong>Gesamt:</strong> ${b.quantity} | <strong>Verfügbar:</strong> ${getAvailable(b)} | <strong>Ausgeliehen:</strong> ${borrowed}</p>
+            ${details ? `<div class="borrow-details">${details}</div>` : ''}
+        </div>`;
+    }).join('');
+};
+
+const populateGenreFilter = () => {
+    const genres = [...new Set(db.getBooks().map(b => b.genre))].sort();
+    $('filter-genre').innerHTML = '<option value="">Alle Genres</option>' + genres.map(g => `<option value="${g}">${g}</option>`).join('');
+};
+
+const render = () => {
+    renderBooks();
+    renderMyBooks();
+    updateDashboard();
+    updateFloatingTimer();
+};
+
+const updateFloatingTimer = () => {
+    const books = db.getBooks();
+    let soonest = null;
+
+    books.forEach(b => {
+        const rec = userRecord(b, user.username);
+        if (rec) {
+            const due = new Date(rec.dueDate).getTime();
+            if (!soonest || due < soonest.due) {
+                soonest = {
+                    due: due,
+                    start: new Date(rec.borrowDate).getTime(),
+                    title: b.title
+                };
+            }
+        }
+    });
+
+    const timerText = document.getElementById('timer-text');
+    const timerProgress = document.getElementById('timer-progress');
+    if (!timerText || !timerProgress) return;
+
+    if (!soonest) {
+        timerText.innerText = 'Keine ausgeliehenen Bücher';
+        timerProgress.style.width = '0%';
+        return;
+    }
+
+    const now = Date.now();
+    const percent = ((now - soonest.start) / (soonest.due - soonest.start)) * 100;
+    const remaining = soonest.due - now;
+    const days = Math.ceil(remaining / (1000 * 60 * 60 * 24));
+
+    timerText.innerText = `${soonest.title} fällig in ${days} Tagen`;
+    timerProgress.style.width = Math.min(100, Math.max(0, percent)) + '%';
+};
+
+setInterval(updateFloatingTimer, 60000);
+updateFloatingTimer();
\ No newline at end of file
