:root {
    /* Color System */
    --bg-primary: #0a0a0f;
    --bg-secondary: #151520;
    --bg-tertiary: #1e1e2e;
    --bg-glass: rgba(30, 30, 46, 0.7);
    
    --text-primary: #e4e4e7;
    --text-secondary: #a1a1aa;
    --text-muted: #71717a;
    
    --accent-primary: #8B5CF6;
    --accent-secondary: #3B82F6;
    --accent-gradient: linear-gradient(135deg, #8B5CF6 0%, #3B82F6 100%);
    
    --success: #10b981;
    --error: #ef4444;
    --warning: #f59e0b;
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 0.5rem;
    --radius-md: 1rem;
    --radius-lg: 1.5rem;
    
    /* Shadows */
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
    --shadow-glow: 0 0 20px rgba(139, 92, 246, 0.3);
    
    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: 300ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-slow: 500ms cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
}

/* Header */
.header {
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-md);
}

.header-content {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-sm) var(--spacing-md);
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--spacing-md);
}

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

.logo h1 {
    font-family: 'Playfair Display', serif;
    font-size: 1.5rem;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav {
    display: flex;
    gap: var(--spacing-sm);
}

.nav-btn {
    background: transparent;
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--text-secondary);
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 0.95rem;
    font-weight: 500;
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    transition: all var(--transition-normal);
}

.nav-btn:hover {
    background: rgba(255, 255, 255, 0.05);
    border-color: rgba(255, 255, 255, 0.2);
    color: var(--text-primary);
    transform: translateY(-2px);
}

.nav-btn.active {
    background: var(--accent-gradient);
    border-color: transparent;
    color: white;
    box-shadow: var(--shadow-glow);
}

/* Main Content */
.main-content {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--spacing-xl) var(--spacing-md);
}

.view {
    display: none;
    animation: fadeIn var(--transition-normal);
}

.view.active {
    display: block;
}

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

/* Library View */
.view-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-lg);
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.view-header h2 {
    font-size: 2rem;
    font-weight: 700;
}

.search-box {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    background: var(--bg-secondary);
    border: 1px solid rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-md);
    padding: var(--spacing-xs) var(--spacing-md);
    transition: all var(--transition-normal);
    min-width: 300px;
}

.search-box:focus-within {
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(139, 92, 246, 0.1);
}

.search-box svg {
    color: var(--text-muted);
}

.search-box input {
    background: transparent;
    border: none;
    outline: none;
    color: var(--text-primary);
    font-size: 0.95rem;
    width: 100%;
}

.search-box input::placeholder {
    color: var(--text-muted);
}

.books-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
}

.book-card {
    background: var(--bg-secondary);
    border: 1px solid rgba(255, 255, 255, 0.05);
    border-radius: var(--radius-lg);
    padding: var(--spacing-md);
    cursor: pointer;
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.book-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: var(--accent-gradient);
    transform: scaleX(0);
    transition: transform var(--transition-normal);
}

.book-card:hover::before {
    transform: scaleX(1);
}

.book-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: rgba(139, 92, 246, 0.3);
}

.book-icon {
    width: 100%;
    height: 180px;
    background: var(--accent-gradient);
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    margin-bottom: var(--spacing-md);
    position: relative;
    overflow: hidden;
}

.book-icon::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, transparent 0%, rgba(0, 0, 0, 0.2) 100%);
}

.book-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--text-primary);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.book-info {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.85rem;
    color: var(--text-secondary);
    gap: var(--spacing-sm);
}

.book-size {
    background: rgba(139, 92, 246, 0.1);
    padding: 0.25rem 0.75rem;
    border-radius: var(--radius-sm);
    font-weight: 500;
}

/* Empty State */
.empty-state {
    text-align: center;
    padding: var(--spacing-xl) var(--spacing-md);
    background: var(--bg-secondary);
    border: 2px dashed rgba(255, 255, 255, 0.1);
    border-radius: var(--radius-lg);
    margin-top: var(--spacing-xl);
}

.empty-icon {
    font-size: 5rem;
    margin-bottom: var(--spacing-md);
    opacity: 0.5;
}

.empty-state h3 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-sm);
}

.empty-state p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-lg);
}

/* Upload View */
.upload-container {
    max-width: 600px;
    margin: 0 auto;
}

.upload-container h2 {
    font-size: 2rem;
    margin-bottom: var(--spacing-xs);
    text-align: center;
}

.upload-subtitle {
    color: var(--text-secondary);
    text-align: center;
    margin-bottom: var(--spacing-xl);
}

.upload-area {
    background: var(--bg-secondary);
    border: 2px dashed rgba(139, 92, 246, 0.3);
    border-radius: var(--radius-lg);
    padding: var(--spacing-xl);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-normal);
}

.upload-area:hover {
    border-color: var(--accent-primary);
    background: rgba(139, 92, 246, 0.05);
    transform: scale(1.02);
}

.upload-area.drag-over {
    border-color: var(--accent-secondary);
    background: rgba(59, 130, 246, 0.1);
    transform: scale(1.05);
}

.upload-icon {
    font-size: 4rem;
    margin-bottom: var(--spacing-md);
}

.upload-area h3 {
    font-size: 1.3rem;
    margin-bottom: var(--spacing-xs);
}

.upload-area p {
    color: var(--text-secondary);
    margin-bottom: var(--spacing-md);
}

.upload-info {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.upload-progress {
    margin-top: var(--spacing-lg);
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: var(--bg-secondary);
    border-radius: var(--radius-sm);
    overflow: hidden;
    margin-bottom: var(--spacing-sm);
}

.progress-fill {
    height: 100%;
    background: var(--accent-gradient);
    width: 0%;
    transition: width var(--transition-normal);
}

.progress-text {
    text-align: center;
    color: var(--text-secondary);
}

.upload-result {
    margin-top: var(--spacing-lg);
    padding: var(--spacing-md);
    border-radius: var(--radius-md);
    text-align: center;
}

.upload-result.success {
    background: rgba(16, 185, 129, 0.1);
    border: 1px solid rgba(16, 185, 129, 0.3);
    color: var(--success);
}

.upload-result.error {
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.3);
    color: var(--error);
}

/* Reader View */
.reader-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
    flex-wrap: wrap;
}

.reader-title {
    flex: 1;
    font-size: 1.3rem;
    font-weight: 600;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.reader-controls {
    display: flex;
    gap: var(--spacing-sm);
}

.pdf-controls {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: var(--spacing-md);
    margin-bottom: var(--spacing-lg);
    padding: var(--spacing-md);
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    flex-wrap: wrap;
}

.control-btn {
    background: var(--bg-tertiary);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
    width: 40px;
    height: 40px;
    border-radius: var(--radius-sm);
    cursor: pointer;
    font-size: 1.2rem;
    transition: all var(--transition-normal);
    display: flex;
    align-items: center;
    justify-content: center;
}

.control-btn:hover:not(:disabled) {
    background: var(--accent-primary);
    border-color: var(--accent-primary);
    transform: scale(1.1);
}

.control-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

.page-info {
    font-size: 0.95rem;
    color: var(--text-secondary);
    font-weight: 500;
}

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

#zoomLevel {
    min-width: 50px;
    text-align: center;
    font-weight: 500;
}

.pdf-viewer {
    background: var(--bg-secondary);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 600px;
    overflow: auto;
}

#pdfCanvas {
    max-width: 100%;
    height: auto;
    box-shadow: var(--shadow-lg);
    border-radius: var(--radius-sm);
}

/* Buttons */
.btn {
    padding: var(--spacing-xs) var(--spacing-md);
    border-radius: var(--radius-md);
    border: none;
    font-size: 0.95rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition-normal);
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
}

.btn-primary {
    background: var(--accent-gradient);
    color: white;
    box-shadow: var(--shadow-sm);
}

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

.btn-secondary {
    background: var(--bg-secondary);
    border: 1px solid rgba(255, 255, 255, 0.1);
    color: var(--text-primary);
}

.btn-secondary:hover {
    background: var(--bg-tertiary);
    border-color: rgba(255, 255, 255, 0.2);
    transform: translateY(-2px);
}

/* Toast Notification */
.toast {
    position: fixed;
    bottom: var(--spacing-lg);
    right: var(--spacing-lg);
    background: var(--bg-glass);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.1);
    padding: var(--spacing-md) var(--spacing-lg);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-lg);
    transform: translateY(150%);
    transition: transform var(--transition-normal);
    z-index: 1000;
    max-width: 400px;
}

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

/* Utility Classes */
.hidden {
    display: none !important;
}

/* Responsive Design */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        gap: var(--spacing-sm);
    }
    
    .view-header {
        flex-direction: column;
        align-items: stretch;
    }
    
    .search-box {
        min-width: auto;
    }
    
    .books-grid {
        grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
        gap: var(--spacing-sm);
    }
    
    .reader-header {
        flex-direction: column;
        align-items: stretch;
    }
    
    .reader-title {
        text-align: center;
    }
    
    .pdf-controls {
        gap: var(--spacing-sm);
    }
    
    .main-content {
        padding: var(--spacing-md) var(--spacing-sm);
    }
}

@media (max-width: 480px) {
    .logo h1 {
        font-size: 1.2rem;
    }
    
    .nav-btn span {
        display: none;
    }
    
    .view-header h2 {
        font-size: 1.5rem;
    }
    
    .books-grid {
        grid-template-columns: 1fr;
    }
    
    .toast {
        left: var(--spacing-sm);
        right: var(--spacing-sm);
        bottom: var(--spacing-sm);
    }
}