* {
    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;
    }
}