/* =============================================
   BOOK STORE - CSS DESIGN SYSTEM
   Colors: Black, Purple, Dark Blue
   ============================================= */

/* CSS Custom Properties */
:root {
    /* Primary Colors */
    --color-black: #0a0a0f;
    --color-black-light: #12121a;
    --color-purple: #8b5cf6;
    --color-purple-light: #a78bfa;
    --color-purple-dark: #6d28d9;
    --color-dark-blue: #1e1b4b;
    --color-blue: #3b82f6;
    --color-blue-light: #60a5fa;
    
    /* Gradients */
    --gradient-primary: linear-gradient(135deg, var(--color-purple) 0%, var(--color-blue) 100%);
    --gradient-dark: linear-gradient(180deg, var(--color-black) 0%, var(--color-dark-blue) 100%);
    --gradient-card: linear-gradient(145deg, rgba(139, 92, 246, 0.1) 0%, rgba(59, 130, 246, 0.05) 100%);
    --gradient-glow: radial-gradient(ellipse at center, rgba(139, 92, 246, 0.15) 0%, transparent 70%);
    
    /* Text Colors */
    --text-primary: #ffffff;
    --text-secondary: #a1a1aa;
    --text-muted: #71717a;
    
    /* Surfaces */
    --surface-glass: rgba(255, 255, 255, 0.05);
    --surface-glass-hover: rgba(255, 255, 255, 0.08);
    --border-glass: rgba(255, 255, 255, 0.1);
    
    /* Shadows */
    --shadow-glow: 0 0 40px rgba(139, 92, 246, 0.3);
    --shadow-card: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    --shadow-button: 0 10px 30px rgba(139, 92, 246, 0.4);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 5rem;
    
    /* Border Radius */
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 30px;
    
    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;
    --transition-slow: 0.5s ease;
    --transition-bounce: 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* Reset & Base Styles */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

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

/* Typography */
h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.2;
    letter-spacing: -0.02em;
}

h1 { font-size: clamp(2.5rem, 6vw, 4rem); }
h2 { font-size: clamp(2rem, 4vw, 3rem); }
h3 { font-size: clamp(1.5rem, 3vw, 2rem); }
h4 { font-size: 1.25rem; }

p { color: var(--text-secondary); }

a {
    color: var(--color-purple-light);
    text-decoration: none;
    transition: var(--transition-fast);
}

a:hover { color: var(--text-primary); }

/* Container */
.container {
    width: 100%;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Background Effects */
.bg-glow {
    position: fixed;
    width: 600px;
    height: 600px;
    background: var(--gradient-glow);
    border-radius: 50%;
    filter: blur(100px);
    pointer-events: none;
    z-index: -1;
}

.bg-glow-1 { top: -200px; left: -200px; }
.bg-glow-2 { bottom: -200px; right: -200px; }

/* =============================================
   NAVIGATION
   ============================================= */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    padding: var(--spacing-md) 0;
    background: rgba(10, 10, 15, 0.8);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border-glass);
    z-index: 1000;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    gap: var(--spacing-lg);
    list-style: none;
}

.nav-links a {
    color: var(--text-secondary);
    font-weight: 500;
    position: relative;
    padding: var(--spacing-xs) 0;
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--gradient-primary);
    transition: var(--transition-normal);
}

.nav-links a:hover::after { width: 100%; }
.nav-links a:hover { color: var(--text-primary); }

/* =============================================
   BUTTONS
   ============================================= */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: 1rem;
    font-weight: 600;
    border: none;
    border-radius: var(--radius-xl);
    cursor: pointer;
    transition: var(--transition-normal);
    text-decoration: none;
}

.btn-primary {
    background: var(--gradient-primary);
    color: var(--text-primary);
    box-shadow: var(--shadow-button);
}

.btn-primary:hover {
    transform: translateY(-3px);
    box-shadow: 0 15px 40px rgba(139, 92, 246, 0.5);
}

.btn-secondary {
    background: var(--surface-glass);
    color: var(--text-primary);
    border: 1px solid var(--border-glass);
}

.btn-secondary:hover {
    background: var(--surface-glass-hover);
    border-color: var(--color-purple);
}

.btn-lg {
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: 1.125rem;
}

.btn-icon {
    width: 50px;
    height: 50px;
    padding: 0;
    border-radius: 50%;
}

/* =============================================
   HERO SECTION
   ============================================= */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    padding-top: 80px;
    position: relative;
    overflow: hidden;
}

.hero-content {
    max-width: 650px;
    animation: fadeInUp 1s ease;
}

.hero-badge {
    display: inline-flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-xs) var(--spacing-sm);
    background: var(--surface-glass);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-xl);
    font-size: 0.875rem;
    color: var(--color-purple-light);
    margin-bottom: var(--spacing-lg);
}

.hero-badge span { animation: pulse 2s infinite; }

.hero h1 {
    margin-bottom: var(--spacing-md);
}

.hero h1 .gradient-text {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-description {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-xl);
    line-height: 1.8;
}

.hero-buttons {
    display: flex;
    gap: var(--spacing-md);
    flex-wrap: wrap;
}

.hero-stats {
    display: flex;
    gap: var(--spacing-xl);
    margin-top: var(--spacing-2xl);
    padding-top: var(--spacing-xl);
    border-top: 1px solid var(--border-glass);
}

.stat {
    text-align: center;
}

.stat-value {
    font-size: 2.5rem;
    font-weight: 800;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    color: var(--text-muted);
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

/* =============================================
   FLOATING BOOKS ANIMATION
   ============================================= */
.floating-books {
    position: absolute;
    right: 5%;
    top: 50%;
    transform: translateY(-50%);
    width: 400px;
    height: 500px;
    perspective: 1000px;
}

.floating-book {
    position: absolute;
    width: 160px;
    height: 240px;
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-card);
    animation: float 6s ease-in-out infinite;
    transition: var(--transition-normal);
}

.floating-book img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.floating-book:nth-child(1) { top: 0; left: 50%; animation-delay: 0s; }
.floating-book:nth-child(2) { top: 30%; left: 0; animation-delay: 1s; }
.floating-book:nth-child(3) { top: 50%; right: 0; animation-delay: 2s; }

.floating-book:hover {
    transform: scale(1.05) rotateY(10deg);
    box-shadow: var(--shadow-glow);
}

/* =============================================
   BOOK CARDS GRID
   ============================================= */
.books-section {
    padding: var(--spacing-2xl) 0;
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.section-header p {
    max-width: 600px;
    margin: var(--spacing-sm) auto 0;
    font-size: 1.125rem;
}

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

.book-card {
    background: var(--gradient-card);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-lg);
    overflow: hidden;
    transition: var(--transition-normal);
    cursor: pointer;
    position: relative;
}

.book-card::before {
    content: '';
    position: absolute;
    inset: 0;
    background: var(--gradient-primary);
    opacity: 0;
    transition: var(--transition-normal);
}

.book-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--shadow-glow);
    border-color: var(--color-purple);
}

.book-card:hover::before { opacity: 0.05; }

.book-cover {
    position: relative;
    height: 320px;
    overflow: hidden;
}

.book-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition-slow);
}

.book-card:hover .book-cover img {
    transform: scale(1.1);
}

.book-overlay {
    position: absolute;
    inset: 0;
    background: linear-gradient(to top, rgba(10, 10, 15, 0.9) 0%, transparent 50%);
    display: flex;
    align-items: flex-end;
    padding: var(--spacing-md);
    opacity: 0;
    transition: var(--transition-normal);
}

.book-card:hover .book-overlay { opacity: 1; }

.book-overlay .btn {
    width: 100%;
}

.book-info {
    padding: var(--spacing-md);
}

.book-title {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-xs);
}

.book-excerpt {
    font-size: 0.875rem;
    color: var(--text-muted);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.book-price {
    margin-top: var(--spacing-sm);
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--color-purple-light);
}

/* =============================================
   BUNDLE OFFER SECTION
   ============================================= */
.bundle-section {
    padding: var(--spacing-2xl) 0;
    background: var(--gradient-card);
    border-top: 1px solid var(--border-glass);
    border-bottom: 1px solid var(--border-glass);
    position: relative;
    overflow: hidden;
}

.bundle-section::before {
    content: '';
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 800px;
    height: 800px;
    background: var(--gradient-glow);
    border-radius: 50%;
    pointer-events: none;
}

.bundle-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-2xl);
    align-items: center;
    position: relative;
    z-index: 1;
}

.bundle-text h2 {
    margin-bottom: var(--spacing-md);
}

.bundle-text .gradient-text {
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.bundle-features {
    list-style: none;
    margin: var(--spacing-lg) 0;
}

.bundle-features li {
    display: flex;
    align-items: center;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-sm);
    color: var(--text-secondary);
}

.bundle-features li::before {
    content: '✓';
    color: var(--color-purple);
    font-weight: bold;
}

.bundle-price {
    display: flex;
    align-items: baseline;
    gap: var(--spacing-sm);
    margin-bottom: var(--spacing-lg);
}

.bundle-price .original {
    font-size: 1.5rem;
    color: var(--text-muted);
    text-decoration: line-through;
}

.bundle-price .sale {
    font-size: 3rem;
    font-weight: 800;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.bundle-savings {
    display: inline-block;
    padding: var(--spacing-xs) var(--spacing-sm);
    background: rgba(139, 92, 246, 0.2);
    color: var(--color-purple-light);
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 0.875rem;
}

.bundle-books {
    display: flex;
    gap: calc(-40px);
    justify-content: center;
}

.bundle-book-preview {
    width: 140px;
    height: 200px;
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-card);
    transition: var(--transition-bounce);
    margin-left: -30px;
}

.bundle-book-preview:first-child { margin-left: 0; }

.bundle-book-preview:hover {
    transform: translateY(-20px) scale(1.05);
    z-index: 10;
}

.bundle-book-preview img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

/* =============================================
   MODAL
   ============================================= */
.modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(10, 10, 15, 0.9);
    backdrop-filter: blur(10px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    opacity: 0;
    visibility: hidden;
    transition: var(--transition-normal);
    padding: var(--spacing-md);
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal {
    background: var(--color-black-light);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-lg);
    max-width: 800px;
    width: 100%;
    max-height: 90vh;
    overflow: auto;
    transform: scale(0.9) translateY(20px);
    transition: var(--transition-bounce);
}

.modal-overlay.active .modal {
    transform: scale(1) translateY(0);
}

.modal-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-md) var(--spacing-lg);
    border-bottom: 1px solid var(--border-glass);
}

.modal-close {
    background: var(--surface-glass);
    border: 1px solid var(--border-glass);
    color: var(--text-primary);
    width: 40px;
    height: 40px;
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    transition: var(--transition-fast);
}

.modal-close:hover {
    background: var(--color-purple);
    border-color: var(--color-purple);
}

.modal-body {
    padding: var(--spacing-lg);
    display: grid;
    grid-template-columns: 200px 1fr;
    gap: var(--spacing-lg);
}

.modal-book-cover {
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-card);
}

.modal-book-cover img {
    width: 100%;
    height: auto;
    display: block;
}

.modal-book-details h3 {
    margin-bottom: var(--spacing-sm);
}

.modal-book-details .price {
    font-size: 2rem;
    font-weight: 700;
    color: var(--color-purple-light);
    margin-bottom: var(--spacing-md);
}

.modal-book-details .description {
    margin-bottom: var(--spacing-lg);
    line-height: 1.8;
}

.modal-footer {
    padding: var(--spacing-md) var(--spacing-lg);
    border-top: 1px solid var(--border-glass);
    display: flex;
    gap: var(--spacing-sm);
    justify-content: flex-end;
}

/* =============================================
   BUNDLE OFFER PAGE
   ============================================= */
.bundle-offer-page {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 100px var(--spacing-md) var(--spacing-2xl);
}

.bundle-offer-card {
    background: var(--gradient-card);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-lg);
    max-width: 700px;
    width: 100%;
    overflow: hidden;
    animation: fadeInUp 0.6s ease;
}

.bundle-offer-header {
    padding: var(--spacing-xl);
    text-align: center;
    background: linear-gradient(180deg, rgba(139, 92, 246, 0.1) 0%, transparent 100%);
    border-bottom: 1px solid var(--border-glass);
}

.bundle-offer-header h1 {
    font-size: 2rem;
    margin-bottom: var(--spacing-xs);
}

.bundle-offer-header p {
    font-size: 1.125rem;
    color: var(--text-secondary);
}

.selected-book-section {
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--border-glass);
}

.selected-book-preview {
    display: flex;
    gap: var(--spacing-md);
    align-items: center;
}

.selected-book-preview img {
    width: 80px;
    height: 120px;
    object-fit: cover;
    border-radius: var(--radius-sm);
}

.selected-book-info h3 {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-xs);
}

.selected-book-info .price {
    color: var(--color-purple-light);
    font-weight: 700;
}

.bundle-upsell-section {
    padding: var(--spacing-lg);
    background: rgba(139, 92, 246, 0.05);
}

.bundle-upsell-section h2 {
    font-size: 1.5rem;
    margin-bottom: var(--spacing-md);
    text-align: center;
}

.bundle-comparison {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--spacing-md);
}

.comparison-option {
    background: var(--surface-glass);
    border: 2px solid var(--border-glass);
    border-radius: var(--radius-md);
    padding: var(--spacing-md);
    text-align: center;
    cursor: pointer;
    transition: var(--transition-normal);
}

.comparison-option:hover,
.comparison-option.selected {
    border-color: var(--color-purple);
    background: var(--surface-glass-hover);
}

.comparison-option.recommended {
    position: relative;
}

.comparison-option.recommended::before {
    content: 'BEST VALUE';
    position: absolute;
    top: -12px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--gradient-primary);
    color: white;
    padding: 4px 12px;
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    font-weight: 700;
}

.comparison-option h3 {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-xs);
}

.comparison-option .price {
    font-size: 1.75rem;
    font-weight: 800;
    background: var(--gradient-primary);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: var(--spacing-xs);
}

.comparison-option .savings {
    color: #22c55e;
    font-weight: 600;
    font-size: 0.875rem;
}

.comparison-option .no-savings {
    color: var(--text-muted);
    font-size: 0.875rem;
}

.bundle-offer-actions {
    padding: var(--spacing-lg);
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.bundle-offer-actions .btn {
    width: 100%;
}

/* =============================================
   SUCCESS PAGE
   ============================================= */
.success-page {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-2xl) var(--spacing-md);
}

.success-container {
    max-width: 600px;
    width: 100%;
    text-align: center;
    animation: fadeInUp 0.8s ease;
}

.success-icon {
    width: 120px;
    height: 120px;
    margin: 0 auto var(--spacing-lg);
    background: linear-gradient(135deg, #22c55e 0%, #16a34a 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    animation: successPop 0.6s ease 0.3s both;
}

.success-icon svg {
    width: 60px;
    height: 60px;
    color: white;
    stroke-width: 3;
}

.checkmark-path {
    stroke-dasharray: 100;
    stroke-dashoffset: 100;
    animation: drawCheck 0.5s ease 0.8s forwards;
}

.success-container h1 {
    margin-bottom: var(--spacing-sm);
    color: #22c55e;
}

.success-container > p {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-xl);
}

.download-section {
    background: var(--gradient-card);
    border: 1px solid var(--border-glass);
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    margin-bottom: var(--spacing-lg);
}

.download-section h2 {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-md);
}

.download-list {
    list-style: none;
}

.download-item {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-sm);
    background: var(--surface-glass);
    border-radius: var(--radius-sm);
    margin-bottom: var(--spacing-xs);
}

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

.download-item-info img {
    width: 40px;
    height: 60px;
    object-fit: cover;
    border-radius: 4px;
}

.download-item .btn {
    padding: var(--spacing-xs) var(--spacing-sm);
    font-size: 0.875rem;
}

/* =============================================
   FAILURE PAGE
   ============================================= */
.failure-page {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-2xl) var(--spacing-md);
}

.failure-container {
    max-width: 500px;
    width: 100%;
    text-align: center;
    animation: fadeInUp 0.8s ease;
}

.failure-icon {
    width: 120px;
    height: 120px;
    margin: 0 auto var(--spacing-lg);
    background: linear-gradient(135deg, #ef4444 0%, #dc2626 100%);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    animation: shake 0.5s ease 0.3s;
}

.failure-icon svg {
    width: 60px;
    height: 60px;
    color: white;
    stroke-width: 3;
}

.failure-container h1 {
    margin-bottom: var(--spacing-sm);
    color: #ef4444;
}

.failure-container > p {
    font-size: 1.125rem;
    margin-bottom: var(--spacing-xl);
}

.failure-actions {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

/* =============================================
   FOOTER
   ============================================= */
.footer {
    padding: var(--spacing-xl) 0;
    border-top: 1px solid var(--border-glass);
    text-align: center;
}

.footer p {
    color: var(--text-muted);
    font-size: 0.875rem;
}

/* =============================================
   ANIMATIONS
   ============================================= */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@keyframes float {
    0%, 100% { transform: translateY(0) rotate(0deg); }
    50% { transform: translateY(-20px) rotate(3deg); }
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

@keyframes successPop {
    0% { transform: scale(0); }
    50% { transform: scale(1.2); }
    100% { transform: scale(1); }
}

@keyframes drawCheck {
    to { stroke-dashoffset: 0; }
}

@keyframes shake {
    0%, 100% { transform: translateX(0); }
    20%, 60% { transform: translateX(-10px); }
    40%, 80% { transform: translateX(10px); }
}

@keyframes slideInRight {
    from {
        opacity: 0;
        transform: translateX(50px);
    }
    to {
        opacity: 1;
        transform: translateX(0);
    }
}

/* Stagger animations for book cards */
.book-card:nth-child(1) { animation: fadeInUp 0.6s ease 0.1s both; }
.book-card:nth-child(2) { animation: fadeInUp 0.6s ease 0.2s both; }
.book-card:nth-child(3) { animation: fadeInUp 0.6s ease 0.3s both; }
.book-card:nth-child(4) { animation: fadeInUp 0.6s ease 0.4s both; }
.book-card:nth-child(5) { animation: fadeInUp 0.6s ease 0.5s both; }
.book-card:nth-child(6) { animation: fadeInUp 0.6s ease 0.6s both; }

/* =============================================
   RESPONSIVE DESIGN
   ============================================= */
@media (max-width: 1024px) {
    .floating-books { display: none; }
    
    .bundle-content { grid-template-columns: 1fr; }
    
    .bundle-books { order: -1; }
    
    .modal-body { grid-template-columns: 1fr; }
    
    .modal-book-cover {
        max-width: 200px;
        margin: 0 auto;
    }
}

@media (max-width: 768px) {
    .hero-stats {
        flex-direction: column;
        gap: var(--spacing-lg);
    }
    
    .hero-buttons {
        flex-direction: column;
    }
    
    .hero-buttons .btn { width: 100%; }
    
    .nav-links { display: none; }
    
    .bundle-comparison {
        grid-template-columns: 1fr;
    }
    
    .comparison-option.recommended { margin-top: var(--spacing-md); }
}

@media (max-width: 480px) {
    .container { padding: 0 var(--spacing-sm); }
    
    .book-cover { height: 280px; }
    
    .bundle-book-preview {
        width: 100px;
        height: 140px;
    }
}

/* =============================================
   LOADING STATES
   ============================================= */
.loading {
    position: relative;
    pointer-events: none;
}

.loading::after {
    content: '';
    position: absolute;
    inset: 0;
    background: rgba(10, 10, 15, 0.8);
    display: flex;
    align-items: center;
    justify-content: center;
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border-glass);
    border-top-color: var(--color-purple);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}