:root {
    /* Color Palette - Sophisticated Library Theme */
    --primary: #2D3E50;
    --primary-light: #3D4E60;
    --primary-dark: #1D2E40;
    --accent: #C9A961;
    --accent-light: #D9B971;
    --secondary: #8B7355;
    --background: #F5F2ED;
    --surface: #FFFFFF;
    --text-primary: #2D3E50;
    --text-secondary: #6B7280;
    --border: #E5E1DA;
    --success: #4A9B7F;
    --warning: #E4A951;
    --danger: #C94A4A;
    --info: #5B8BB5;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 12px;
    --radius-lg: 20px;
    
    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(45, 62, 80, 0.08);
    --shadow-md: 0 4px 16px rgba(45, 62, 80, 0.12);
    --shadow-lg: 0 8px 32px rgba(45, 62, 80, 0.16);
    
    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-base: 250ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 400ms cubic-bezier(0.4, 0, 0.2, 1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Inter', sans-serif;
    background: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
    overflow-x: hidden;
}

/* Background Elements */
.bg-texture {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-image: 
        repeating-linear-gradient(0deg, transparent, transparent 2px, rgba(201, 169, 97, 0.03) 2px, rgba(201, 169, 97, 0.03) 4px);
    pointer-events: none;
    z-index: 0;
}

.bg-gradient {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at 20% 20%, rgba(201, 169, 97, 0.08) 0%, transparent 50%),
                radial-gradient(circle at 80% 80%, rgba(139, 115, 85, 0.08) 0%, transparent 50%);
    pointer-events: none;
    z-index: 0;
}

/* Container Layout */
.container {
    display: flex;
    min-height: 100vh;
    position: relative;
    z-index: 1;
}

/* Sidebar */
.sidebar {
    width: 280px;
    background: var(--surface);
    border-right: 1px solid var(--border);
    padding: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    position: sticky;
    top: 0;
    height: 100vh;
    overflow-y: auto;
    animation: slideInLeft 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes slideInLeft {
    from {
        opacity: 0;
        transform: translateX(-20px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

.logo {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-xl);
    padding-bottom: var(--spacing-lg);
    border-bottom: 2px solid var(--accent);
}

.logo-icon {
    font-size: 2.5rem;
    animation: float 3s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0px); }
    50% { transform: translateY(-5px); }
}

.logo h1 {
    font-family: 'Playfair Display', serif;
    font-size: 1.75rem;
    font-weight: 900;
    color: var(--primary);
    letter-spacing: -0.02em;
}

/* Navigation */
.nav-menu {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.nav-item {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    padding: var(--spacing-sm) var(--spacing-md);
    background: transparent;
    border: none;
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-base);
    position: relative;
    overflow: hidden;
}

.nav-item::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 3px;
    background: var(--accent);
    transform: scaleY(0);
    transition: transform var(--transition-base);
}

.nav-item:hover {
    background: var(--background);
    color: var(--text-primary);
}

.nav-item.active {
    background: linear-gradient(135deg, rgba(201, 169, 97, 0.15) 0%, rgba(201, 169, 97, 0.05) 100%);
    color: var(--accent);
    font-weight: 600;
}

.nav-item.active::before {
    transform: scaleY(1);
}

.nav-icon {
    font-size: 1.25rem;
}

/* Sidebar Footer */
.sidebar-footer {
    margin-top: auto;
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--border);
}

.user-profile {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
}

.user-avatar {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    background: linear-gradient(135deg, var(--accent) 0%, var(--secondary) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-weight: 700;
    font-size: 0.9rem;
}

.user-info {
    flex: 1;
}

.user-name {
    font-weight: 600;
    font-size: 0.9rem;
    color: var(--text-primary);
}

.user-role {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

/* Main Content */
.main-content {
    flex: 1;
    padding: var(--spacing-xl);
    max-width: 1400px;
    animation: fadeIn 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Views */
.view {
    display: none;
    animation: fadeIn 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

.view.active {
    display: block;
}

/* Page Header */
.page-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-xl);
    gap: var(--spacing-md);
}

.page-title {
    font-family: 'Playfair Display', serif;
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: var(--spacing-xs);
}

.page-subtitle {
    color: var(--text-secondary);
    font-size: 1rem;
}

/* Buttons */
.btn-primary,
.btn-secondary {
    padding: 0.75rem 1.5rem;
    border: none;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 0.95rem;
    cursor: pointer;
    transition: all var(--transition-base);
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.btn-primary {
    background: linear-gradient(135deg, var(--accent) 0%, var(--secondary) 100%);
    color: white;
    box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: var(--surface);
    color: var(--text-primary);
    border: 2px solid var(--border);
}

.btn-secondary:hover {
    border-color: var(--accent);
    color: var(--accent);
}

/* Stats Grid */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-xl);
}

.stat-card {
    background: var(--surface);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
    transition: all var(--transition-base);
    border: 1px solid var(--border);
    animation: scaleIn 0.4s cubic-bezier(0.4, 0, 0.2, 1);
    animation-fill-mode: backwards;
}

.stat-card:nth-child(1) { animation-delay: 0.1s; }
.stat-card:nth-child(2) { animation-delay: 0.2s; }
.stat-card:nth-child(3) { animation-delay: 0.3s; }
.stat-card:nth-child(4) { animation-delay: 0.4s; }

@keyframes scaleIn {
    from {
        opacity: 0;
        transform: scale(0.9);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}

.stat-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

.stat-icon {
    width: 60px;
    height: 60px;
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.75rem;
}

.stat-icon.books {
    background: linear-gradient(135deg, rgba(246, 197, 222, 0.2) 0%, rgba(201, 169, 97, 0.1) 100%);
}

.stat-icon.members {
    background: linear-gradient(135deg, rgba(74, 155, 127, 0.2) 0%, rgba(74, 155, 127, 0.1) 100%);
}

.stat-icon.borrowed {
    background: linear-gradient(135deg, rgba(91, 139, 181, 0.2) 0%, rgba(91, 139, 181, 0.1) 100%);
}

.stat-icon.overdue {
    background: linear-gradient(135deg, rgba(228, 169, 81, 0.2) 0%, rgba(228, 169, 81, 0.1) 100%);
}

.stat-value {
    font-family: 'Space Mono', monospace;
    font-size: 2rem;
    font-weight: 700;
    color: var(--primary);
}

.stat-label {
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 500;
}

/* Dashboard Content */
.dashboard-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-lg);
}

.recent-activities,
.popular-books {
    background: var(--surface);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border);
}

.section-title {
    font-family: 'Playfair Display', serif;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--accent);
}

.activities-list,
.popular-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.activity-item,
.popular-item {
    padding: var(--spacing-sm);
    border-radius: var(--radius-sm);
    background: var(--background);
    transition: all var(--transition-fast);
}

.activity-item:hover,
.popular-item:hover {
    background: rgba(201, 169, 97, 0.1);
    transform: translateX(4px);
}

.activity-time,
.popular-count {
    font-size: 0.8rem;
    color: var(--text-secondary);
    font-family: 'Space Mono', monospace;
}

/* Filters Bar */
.filters-bar {
    display: flex;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
    flex-wrap: wrap;
}

.search-input,
.filter-select {
    padding: 0.75rem 1rem;
    border: 2px solid var(--border);
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    background: var(--surface);
    color: var(--text-primary);
    transition: all var(--transition-base);
}

.search-input {
    flex: 1;
    min-width: 250px;
}

.search-input:focus,
.filter-select:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(201, 169, 97, 0.1);
}

/* Table */
.table-container {
    background: var(--surface);
    border-radius: var(--radius-lg);
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border);
}

.data-table {
    width: 100%;
    border-collapse: collapse;
}

.data-table thead {
    background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
    color: white;
}

.data-table th {
    padding: var(--spacing-md);
    text-align: left;
    font-weight: 600;
    font-size: 0.9rem;
    letter-spacing: 0.02em;
    text-transform: uppercase;
}

.data-table tbody tr {
    border-bottom: 1px solid var(--border);
    transition: all var(--transition-fast);
}

.data-table tbody tr:hover {
    background: rgba(201, 169, 97, 0.05);
}

.data-table td {
    padding: var(--spacing-md);
    font-size: 0.95rem;
}

/* Status Badges */
.status-badge {
    display: inline-block;
    padding: 0.35rem 0.75rem;
    border-radius: 100px;
    font-size: 0.8rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.03em;
}

.status-badge.available {
    background: rgba(74, 155, 127, 0.15);
    color: var(--success);
}

.status-badge.borrowed {
    background: rgba(91, 139, 181, 0.15);
    color: var(--info);
}

.status-badge.overdue {
    background: rgba(228, 169, 81, 0.15);
    color: var(--warning);
}

.status-badge.active {
    background: rgba(74, 155, 127, 0.15);
    color: var(--success);
}

.status-badge.inactive {
    background: rgba(107, 114, 128, 0.15);
    color: var(--text-secondary);
}

.status-badge.returned {
    background: rgba(107, 114, 128, 0.15);
    color: var(--text-secondary);
}

/* Action Buttons */
.action-btn {
    padding: 0.4rem 0.8rem;
    margin: 0 0.25rem;
    border: none;
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
}

.action-btn.edit {
    background: rgba(91, 139, 181, 0.15);
    color: var(--info);
}

.action-btn.delete {
    background: rgba(201, 74, 74, 0.15);
    color: var(--danger);
}

.action-btn.return {
    background: rgba(74, 155, 127, 0.15);
    color: var(--success);
}

.action-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

/* Modal */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(45, 62, 80, 0.6);
    backdrop-filter: blur(4px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    animation: fadeIn 0.3s ease;
}

.modal.active {
    display: flex;
}

.modal-content {
    background: var(--surface);
    border-radius: var(--radius-lg);
    width: 90%;
    max-width: 500px;
    max-height: 90vh;
    overflow-y: auto;
    box-shadow: var(--shadow-lg);
    animation: slideUp 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

@keyframes slideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-lg);
    border-bottom: 2px solid var(--accent);
}

.modal-header h3 {
    font-family: 'Playfair Display', serif;
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
}

.modal-close {
    background: none;
    border: none;
    font-size: 2rem;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    line-height: 1;
}

.modal-close:hover {
    color: var(--danger);
    transform: rotate(90deg);
}

.modal-form {
    padding: var(--spacing-lg);
}

.form-group {
    margin-bottom: var(--spacing-md);
}

.form-group label {
    display: block;
    margin-bottom: var(--spacing-xs);
    font-weight: 600;
    color: var(--text-primary);
    font-size: 0.9rem;
}

.form-group input,
.form-group select,
.form-group textarea {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border);
    border-radius: var(--radius-md);
    font-size: 0.95rem;
    font-family: inherit;
    background: var(--surface);
    color: var(--text-primary);
    transition: all var(--transition-base);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--accent);
    box-shadow: 0 0 0 3px rgba(201, 169, 97, 0.1);
}

.modal-actions {
    display: flex;
    gap: var(--spacing-sm);
    margin-top: var(--spacing-lg);
}

/* Settings */
.settings-container {
    display: grid;
    gap: var(--spacing-lg);
}

.settings-card {
    background: var(--surface);
    padding: var(--spacing-lg);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border);
}

.settings-card h3 {
    font-family: 'Playfair Display', serif;
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: var(--spacing-md);
    padding-bottom: var(--spacing-sm);
    border-bottom: 2px solid var(--accent);
}

.settings-actions {
    display: flex;
    gap: var(--spacing-md);
}

/* Toast Notifications */
.toast {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    padding: 1rem 1.5rem;
    background: var(--primary);
    color: white;
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    transform: translateY(100px);
    opacity: 0;
    transition: all var(--transition-base);
    z-index: 2000;
    font-weight: 600;
}

.toast.show {
    transform: translateY(0);
    opacity: 1;
}

.toast.success {
    background: var(--success);
}

.toast.error {
    background: var(--danger);
}

.toast.warning {
    background: var(--warning);
}

/* Responsive Design */
@media (max-width: 1024px) {
    .dashboard-content {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .container {
        flex-direction: column;
    }
    
    .sidebar {
        width: 100%;
        height: auto;
        position: relative;
    }
    
    .main-content {
        padding: var(--spacing-md);
    }
    
    .page-header {
        flex-direction: column;
        align-items: flex-start;
    }
    
    .stats-grid {
        grid-template-columns: 1fr;
    }
    
    .filters-bar {
        flex-direction: column;
    }
    
    .search-input {
        width: 100%;
    }
    
    .table-container {
        overflow-x: auto;
    }
}

/* Scrollbar Styling */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}

::-webkit-scrollbar-track {
    background: var(--background);
}

::-webkit-scrollbar-thumb {
    background: var(--accent);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--secondary);
}