/* =====================================================
   BOX COLLECTION — Design System & Styles
   =====================================================
   Mobile-first, premium e-commerce design.
   Palette: Deep navy + royal blue + white + amber CTAs
   Typography: Inter (Google Fonts)
   ===================================================== */

/* ---- Google Fonts ---- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=Playfair+Display:ital,wght@0,700;0,800;1,700;1,800&display=swap');

/* =====================================================
   1. DESIGN TOKENS
   ===================================================== */
:root {
  /* Colors — Light blue / white theme */
  --color-primary: #1e3a6e;
  --color-primary-light: #3b6cf5;
  --color-primary-lighter: #5b8af7;
  --color-primary-dark: #142952;
  --color-primary-50: #eef2ff;
  --color-primary-100: #dbe4ff;
  --color-accent: #3b6cf5;
  --color-accent-hover: #2856d9;
  --color-accent-light: #eef2ff;
  --color-bg: #ffffff;
  --color-bg-alt: #f0f4fa;
  --color-bg-hero: #edf1fb;
  --color-bg-dark: #101830;
  --color-surface: #ffffff;
  --color-text: #1a2356;
  --color-text-secondary: #5c6a8a;
  --color-text-light: #8b95b3;
  --color-text-white: #ffffff;
  --color-border: #dde3f0;
  --color-border-light: #eef2fa;
  --color-success: #10b981;
  --color-success-bg: #ecfdf5;
  --color-error: #ef4444;
  --color-error-bg: #fef2f2;
  --color-warning: #f59e0b;
  --color-overlay: rgba(15, 29, 50, 0.6);

  /* Serif font for accent headings */
  --font-serif: 'Playfair Display', Georgia, serif;

  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --fs-2xs: 0.625rem;
  --fs-xs: 0.75rem;
  --fs-sm: 0.875rem;
  --fs-base: 1rem;
  --fs-lg: 1.125rem;
  --fs-xl: 1.25rem;
  --fs-2xl: 1.5rem;
  --fs-3xl: 1.875rem;
  --fs-4xl: 2.25rem;
  --fs-5xl: 3rem;
  --fs-6xl: 3.75rem;
  --lh-tight: 1.2;
  --lh-base: 1.5;
  --lh-relaxed: 1.7;

  /* Spacing */
  --sp-1: 0.25rem;
  --sp-2: 0.5rem;
  --sp-3: 0.75rem;
  --sp-4: 1rem;
  --sp-5: 1.25rem;
  --sp-6: 1.5rem;
  --sp-8: 2rem;
  --sp-10: 2.5rem;
  --sp-12: 3rem;
  --sp-16: 4rem;
  --sp-20: 5rem;
  --sp-24: 6rem;

  /* Borders */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;
  --radius-full: 9999px;

  /* Shadows */
  --shadow-xs: 0 1px 2px rgba(0,0,0,0.04);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.07), 0 2px 4px -2px rgba(0,0,0,0.05);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -4px rgba(0,0,0,0.05);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.1), 0 8px 10px -6px rgba(0,0,0,0.04);
  --shadow-2xl: 0 25px 50px -12px rgba(0,0,0,0.15);
  --shadow-glow: 0 0 20px rgba(59,108,245,0.25);
  --shadow-accent-glow: 0 0 24px rgba(59,108,245,0.35);
  --shadow-card-hover: 0 20px 40px -8px rgba(26,35,86,0.15);

  /* Transitions */
  --ease-out: cubic-bezier(0.4, 0, 0.2, 1);
  --ease-bounce: cubic-bezier(0.34, 1.56, 0.64, 1);
  --t-fast: 150ms var(--ease-out);
  --t-base: 250ms var(--ease-out);
  --t-slow: 350ms var(--ease-out);
  --t-drawer: 400ms cubic-bezier(0.32, 0.72, 0, 1);

  /* Z-index */
  --z-base: 1;
  --z-dropdown: 100;
  --z-sticky: 200;
  --z-overlay: 300;
  --z-drawer: 350;
  --z-modal: 400;
  --z-toast: 500;

  /* Layout */
  --header-height: 72px;
  --max-width: 1200px;
  --drawer-width: 420px;
}


/* =====================================================
   2. RESET & BASE
   ===================================================== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-family);
  font-size: var(--fs-base);
  line-height: var(--lh-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

body.drawer-open,
body.modal-open {
  overflow: hidden;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: inherit;
  text-decoration: none;
}

button {
  font: inherit;
  cursor: pointer;
  border: none;
  background: none;
  color: inherit;
}

ul, ol { list-style: none; }
input, textarea, select { font: inherit; }

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}


/* =====================================================
   3. LAYOUT
   ===================================================== */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--sp-5);
}

.page-content {
  padding-top: var(--header-height);
  min-height: 100vh;
}


/* =====================================================
   4. TYPOGRAPHY
   ===================================================== */
h1, h2, h3, h4, h5, h6 {
  font-weight: 700;
  line-height: var(--lh-tight);
  color: var(--color-text);
}

.section-title {
  font-size: var(--fs-2xl);
  font-weight: 800;
  margin-bottom: var(--sp-2);
}

.section-subtitle {
  font-size: var(--fs-base);
  color: var(--color-text-secondary);
  margin-bottom: var(--sp-10);
}


/* =====================================================
   5. BUTTONS
   ===================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--sp-2);
  padding: var(--sp-3) var(--sp-6);
  font-size: var(--fs-sm);
  font-weight: 600;
  border-radius: var(--radius-lg);
  transition: all var(--t-base);
  position: relative;
  overflow: hidden;
  white-space: nowrap;
}

.btn::after {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(255,255,255,0.15);
  opacity: 0;
  transition: opacity var(--t-fast);
}

.btn:hover::after { opacity: 1; }
.btn:active { transform: scale(0.97); }

.btn--primary {
  background: linear-gradient(135deg, #3b6cf5 0%, #2856d9 100%);
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(59,108,245,0.35);
}

.btn--primary:hover {
  box-shadow: var(--shadow-accent-glow);
  transform: translateY(-1px);
  background: linear-gradient(135deg, #4a7af7 0%, #3362e8 100%);
}

.btn--secondary {
  background: var(--color-primary-light);
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(37,99,235,0.25);
}

.btn--secondary:hover {
  background: var(--color-primary-lighter);
  box-shadow: var(--shadow-glow);
  transform: translateY(-1px);
}

.btn--outline {
  background: transparent;
  color: var(--color-primary-light);
  border: 2px solid var(--color-primary-light);
}

.btn--outline:hover {
  background: var(--color-primary-light);
  color: #ffffff;
}

.btn--ghost {
  background: transparent;
  color: var(--color-text-secondary);
}

.btn--ghost:hover {
  color: var(--color-primary-light);
  background: var(--color-primary-50);
}

.btn--lg {
  padding: var(--sp-4) var(--sp-8);
  font-size: var(--fs-base);
  border-radius: var(--radius-xl);
}

.btn--full { width: 100%; }

.btn--disabled,
.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
  box-shadow: none;
}


/* =====================================================
   6. HEADER
   ===================================================== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: rgba(255,255,255,0.82);
  backdrop-filter: blur(16px) saturate(180%);
  -webkit-backdrop-filter: blur(16px) saturate(180%);
  border-bottom: 1px solid rgba(226,232,240,0.6);
  z-index: var(--z-sticky);
  transition: background var(--t-base), box-shadow var(--t-base);
}

.header.scrolled {
  background: rgba(255,255,255,0.95);
  box-shadow: var(--shadow-md);
}

.header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--sp-5);
}

.header__logo {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  font-size: var(--fs-xl);
  font-weight: 800;
  color: var(--color-primary);
  letter-spacing: -0.02em;
}

.header__logo-img {
  height: 48px;
  width: auto;
  display: block;
}

.header__nav {
  display: none;
  align-items: center;
  gap: var(--sp-8);
}

.header__nav a {
  font-size: var(--fs-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: color var(--t-fast);
  position: relative;
}

.header__nav a:hover,
.header__nav a.active {
  color: var(--color-primary-light);
}

.header__nav a.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--color-primary-light);
  border-radius: var(--radius-full);
}

.header__actions {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
}

.header__quality-btn {
  display: none;
  align-items: center;
  gap: var(--sp-2);
  padding: var(--sp-2) var(--sp-4);
  font-size: var(--fs-sm);
  font-weight: 500;
  color: var(--color-primary-light);
  border: 1.5px solid var(--color-primary-100);
  border-radius: var(--radius-full);
  transition: all var(--t-fast);
  background: transparent;
}

.header__quality-btn:hover {
  background: var(--color-primary-50);
  border-color: var(--color-primary-light);
}

.header__cart-btn {
  position: relative;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-lg);
  transition: background var(--t-fast);
}

.header__cart-btn:hover {
  background: var(--color-primary-50);
}

.header__cart-btn svg {
  width: 24px;
  height: 24px;
  color: var(--color-primary);
}

.header__cart-badge {
  position: absolute;
  top: 4px;
  right: 4px;
  min-width: 20px;
  height: 20px;
  padding: 0 5px;
  background: var(--color-accent);
  color: #ffffff;
  font-size: var(--fs-2xs);
  font-weight: 700;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  transform: scale(0);
  transition: transform var(--t-fast);
  animation: none;
}

.header__cart-badge.visible {
  transform: scale(1);
}

.header__cart-badge.pop {
  animation: badgePop 400ms var(--ease-bounce);
}

/* Mobile menu toggle */
.header__menu-btn {
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-lg);
}

.header__menu-btn svg {
  width: 24px;
  height: 24px;
}

/* Mobile nav overlay */
.mobile-nav {
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(255,255,255,0.98);
  backdrop-filter: blur(20px);
  z-index: var(--z-overlay);
  display: flex;
  flex-direction: column;
  padding: var(--sp-8) var(--sp-5);
  gap: var(--sp-2);
  transform: translateY(-10px);
  opacity: 0;
  pointer-events: none;
  transition: all var(--t-base);
}

.mobile-nav.open {
  transform: translateY(0);
  opacity: 1;
  pointer-events: auto;
}

.mobile-nav a {
  display: flex;
  align-items: center;
  gap: var(--sp-4);
  padding: var(--sp-4) var(--sp-5);
  font-size: var(--fs-lg);
  font-weight: 600;
  color: var(--color-text);
  border-radius: var(--radius-xl);
  transition: all var(--t-fast);
}

.mobile-nav a:hover,
.mobile-nav a.active {
  background: var(--color-primary-50);
  color: var(--color-primary-light);
}


/* =====================================================
   7. HERO SECTION — Light two-column layout
   ===================================================== */
.hero {
  position: relative;
  background: linear-gradient(180deg, var(--color-bg-hero) 0%, #dde5f7 60%, #c8d5f0 100%);
  overflow: hidden;
  padding: var(--sp-6) 0 var(--sp-16);
}

/* Soft wave at the bottom */
.hero::after {
  content: '';
  position: absolute;
  bottom: -2px;
  left: 0;
  right: 0;
  height: 60px;
  background: var(--color-bg);
  border-radius: 50% 50% 0 0 / 100% 100% 0 0;
}

.hero__inner {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-8);
  align-items: center;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--sp-5);
}

.hero__content {
  position: relative;
  z-index: var(--z-base);
  max-width: 560px;
  padding-bottom: var(--sp-4);
}

.hero__badge {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  padding: var(--sp-2) var(--sp-5);
  background: rgba(59,108,245,0.1);
  border: 1px solid rgba(59,108,245,0.2);
  border-radius: var(--radius-full);
  color: var(--color-primary-light);
  font-size: var(--fs-xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  margin-bottom: var(--sp-6);
}

.hero__title {
  font-size: var(--fs-4xl);
  font-weight: 800;
  color: var(--color-text);
  line-height: 1.15;
  margin-bottom: var(--sp-5);
  letter-spacing: -0.02em;
}

.hero__title em {
  font-family: var(--font-serif);
  font-style: italic;
  font-weight: 700;
  color: var(--color-primary-light);
}

.hero__subtitle {
  font-size: var(--fs-base);
  color: var(--color-text-secondary);
  line-height: var(--lh-relaxed);
  margin-bottom: var(--sp-8);
  max-width: 420px;
}

.hero__actions {
  display: flex;
  gap: var(--sp-4);
  flex-wrap: wrap;
  margin-bottom: var(--sp-8);
}

/* Feature pills */
.hero__features {
  display: flex;
  gap: var(--sp-3);
  flex-wrap: wrap;
}

.hero__feature {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  padding: var(--sp-2) var(--sp-4);
  background: rgba(255,255,255,0.7);
  border: 1px solid rgba(255,255,255,0.9);
  border-radius: var(--radius-full);
  font-size: var(--fs-xs);
  font-weight: 500;
  color: var(--color-text-secondary);
  backdrop-filter: blur(4px);
}

/* Hero image column */
.hero__visual {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--sp-6) 0;
}

.hero__image {
  width: 100%;
  max-width: 480px;
  height: auto;
  border-radius: var(--radius-2xl);
  object-fit: cover;
  position: relative;
  z-index: var(--z-base);
  box-shadow: var(--shadow-xl);
}

/* Floating stat badge */
.hero__stat {
  position: absolute;
  bottom: var(--sp-8);
  left: var(--sp-4);
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(10px);
  border-radius: var(--radius-xl);
  padding: var(--sp-3) var(--sp-5);
  box-shadow: var(--shadow-lg);
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  z-index: 2;
}

.hero__stat-number {
  font-size: var(--fs-2xl);
  font-weight: 800;
  color: var(--color-primary-light);
  line-height: 1;
}

.hero__stat-label {
  font-size: var(--fs-2xs);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-secondary);
  line-height: 1.3;
}


/* =====================================================
   8. PRODUCT GRID & CARDS
   ===================================================== */
.products-section {
  padding: var(--sp-16) 0;
}

.products-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-6);
}

.product-card {
  background: var(--color-surface);
  border-radius: var(--radius-2xl);
  overflow: hidden;
  border: 1px solid var(--color-border-light);
  box-shadow: var(--shadow-sm);
  transition: all var(--t-slow);
  cursor: pointer;
  position: relative;
}

.product-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-card-hover);
  border-color: transparent;
}

.product-card__image {
  position: relative;
  width: 100%;
  aspect-ratio: 4/3;
  overflow: hidden;
}

.product-card__image-bg {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  color: rgba(255,255,255,0.9);
  transition: transform var(--t-slow);
}

.product-card:hover .product-card__image-bg {
  transform: scale(1.05);
}

.product-card__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.carousel__img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  border-radius: var(--radius-2xl);
}

.carousel__thumb-img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
  border-radius: var(--radius-md);
}

.product-card__badge {
  position: absolute;
  top: var(--sp-4);
  left: var(--sp-4);
  padding: var(--sp-1) var(--sp-3);
  background: var(--color-accent);
  color: #ffffff;
  font-size: var(--fs-xs);
  font-weight: 700;
  border-radius: var(--radius-full);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.product-card__content {
  padding: var(--sp-6);
}

.product-card__name {
  font-size: var(--fs-xl);
  font-weight: 700;
  margin-bottom: var(--sp-2);
  color: var(--color-text);
}

.product-card__desc {
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
  line-height: var(--lh-relaxed);
  margin-bottom: var(--sp-4);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.product-card__footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.product-card__price {
  font-size: var(--fs-2xl);
  font-weight: 800;
  color: var(--color-primary);
}

.product-card__price span {
  font-size: var(--fs-base);
  font-weight: 500;
  color: var(--color-text-secondary);
}

.product-card__action .btn {
  padding: var(--sp-2) var(--sp-5);
}


/* ---- Customize Your Own Combo Card ---- */
.customize-cta-card {
  background: linear-gradient(135deg, var(--color-primary-50) 0%, var(--color-primary-100) 100%);
  border: 2px dashed var(--color-primary-light);
  border-radius: var(--radius-2xl);
  padding: var(--sp-10) var(--sp-8);
  text-align: center;
  transition: all var(--t-base);
  cursor: pointer;
}

.customize-cta-card:hover {
  background: linear-gradient(135deg, var(--color-primary-100) 0%, #c7d2fe 100%);
  border-style: solid;
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.customize-cta-card__icon {
  width: 72px;
  height: 72px;
  margin: 0 auto var(--sp-5);
  background: linear-gradient(135deg, var(--color-primary-light) 0%, var(--color-primary) 100%);
  border-radius: var(--radius-2xl);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  color: white;
}

.customize-cta-card__title {
  font-size: var(--fs-2xl);
  font-weight: 800;
  color: var(--color-primary);
  margin-bottom: var(--sp-2);
}

.customize-cta-card__desc {
  color: var(--color-text-secondary);
  margin-bottom: var(--sp-6);
}

.customize-cta-card__prices {
  display: flex;
  justify-content: center;
  gap: var(--sp-6);
  margin-bottom: var(--sp-6);
}

.customize-cta-card__tier {
  padding: var(--sp-3) var(--sp-5);
  background: rgba(255,255,255,0.8);
  border-radius: var(--radius-lg);
  font-weight: 600;
  color: var(--color-primary);
}

.customize-cta-card__tier strong {
  color: var(--color-accent);
}


/* =====================================================
   9. PRODUCT DETAIL
   ===================================================== */
.product-detail {
  padding: var(--sp-8) 0 var(--sp-16);
}

.product-detail__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-10);
}

/* Carousel */
.carousel {
  position: relative;
  border-radius: var(--radius-2xl);
  overflow: hidden;
}

.carousel__main {
  width: 100%;
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 5rem;
  color: rgba(255,255,255,0.8);
  border-radius: var(--radius-2xl);
  transition: opacity var(--t-base);
}

.carousel__thumbnails {
  display: flex;
  gap: var(--sp-3);
  margin-top: var(--sp-4);
  overflow-x: auto;
  padding-bottom: var(--sp-2);
  scrollbar-width: none;
}

.carousel__thumbnails::-webkit-scrollbar { display: none; }

.carousel__thumb {
  flex-shrink: 0;
  width: 72px;
  height: 72px;
  border-radius: var(--radius-lg);
  border: 2px solid transparent;
  cursor: pointer;
  transition: all var(--t-fast);
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}

.carousel__thumb.active,
.carousel__thumb:hover {
  border-color: var(--color-primary-light);
  box-shadow: 0 0 0 3px rgba(37,99,235,0.15);
}

/* Product info */
.product-info {
  display: flex;
  flex-direction: column;
  gap: var(--sp-6);
}

.product-info__name {
  font-size: var(--fs-3xl);
  font-weight: 800;
  letter-spacing: -0.02em;
}

.product-info__price {
  font-size: var(--fs-3xl);
  font-weight: 800;
  color: var(--color-primary-light);
}

.product-info__desc {
  color: var(--color-text-secondary);
  line-height: var(--lh-relaxed);
  font-size: var(--fs-base);
}

.product-info__books-title {
  font-size: var(--fs-sm);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-light);
  margin-bottom: var(--sp-3);
}

.product-info__books-list {
  display: flex;
  flex-direction: column;
  gap: var(--sp-2);
}

.product-info__book-item {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  padding: var(--sp-3) var(--sp-4);
  background: var(--color-bg-alt);
  border-radius: var(--radius-lg);
  font-size: var(--fs-sm);
  font-weight: 500;
}

.product-info__book-item::before {
  content: '•';
  color: var(--color-primary-light);
  font-size: var(--fs-lg);
  line-height: 1;
}

.product-info__book-item--surprise {
  background: linear-gradient(135deg, #ff416c 0%, #ff4b2b 100%);
  color: #ffffff;
  font-weight: 700;
  border: 1.5px solid #ffd700;
  box-shadow: 0 4px 15px rgba(255, 65, 108, 0.4);
  position: relative;
  overflow: hidden;
  transition: transform 200ms ease, box-shadow 200ms ease;
  animation: surprisePulse 2.5s infinite ease-in-out;
}

.product-info__book-item--surprise:hover {
  transform: translateY(-2px) scale(1.01);
  box-shadow: 0 6px 20px rgba(255, 65, 108, 0.6);
}

.product-info__book-item--surprise::before {
  display: none;
}

.surprise-badge-icon {
  font-size: 1.2rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  animation: giftBounce 1.5s infinite ease-in-out;
}

.cart-surprise-badge {
  color: #ff416c;
  font-weight: 700;
  background: rgba(255, 65, 108, 0.12);
  padding: 1px 6px;
  border-radius: 4px;
  display: inline-block;
}

@keyframes surprisePulse {
  0%, 100% {
    box-shadow: 0 4px 15px rgba(255, 65, 108, 0.4);
    border-color: #ffd700;
  }
  50% {
    box-shadow: 0 6px 22px rgba(255, 215, 0, 0.7);
    border-color: #ffffff;
  }
}

@keyframes giftBounce {
  0%, 100% { transform: translateY(0) rotate(0deg); }
  50% { transform: translateY(-3px) rotate(-8deg); }
}

/* Quantity selector */
.quantity-selector {
  display: flex;
  align-items: center;
  gap: var(--sp-1);
  background: var(--color-bg-alt);
  border-radius: var(--radius-lg);
  padding: var(--sp-1);
  width: fit-content;
}

.quantity-selector__btn {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  font-size: var(--fs-lg);
  font-weight: 600;
  color: var(--color-text);
  transition: all var(--t-fast);
}

.quantity-selector__btn:hover {
  background: var(--color-primary-light);
  color: white;
}

.quantity-selector__value {
  width: 48px;
  text-align: center;
  font-size: var(--fs-lg);
  font-weight: 700;
}

.product-detail__actions {
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
  width: 100%;
}

.product-detail__actions .btn {
  width: 100%;
  margin: 0;
}

.product-detail__actions #buy-now-btn {
  background: var(--color-success);
  border-color: var(--color-success);
  color: white;
}

.product-detail__actions #buy-now-btn:hover {
  background: var(--color-success-dark, #059669);
  border-color: var(--color-success-dark, #059669);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

@media (min-width: 768px) {
  .product-detail__actions {
    flex-direction: row;
    flex-wrap: wrap;
    gap: var(--sp-4);
  }

  .product-detail__actions #add-to-cart-btn,
  .product-detail__actions #buy-now-btn {
    flex: 1;
    min-width: 180px;
    width: auto;
  }

  .product-detail__actions #product-quality-btn {
    width: 100%;
  }
}


/* =====================================================
   10. CUSTOMIZATION PAGE
   ===================================================== */
.customize-page {
  padding: var(--sp-8) 0 var(--sp-16);
}

.customize-page__header {
  text-align: center;
  margin-bottom: var(--sp-8);
}

/* Tier toggle */
.tier-toggle {
  display: flex;
  gap: var(--sp-2);
  background: var(--color-bg-alt);
  border-radius: var(--radius-xl);
  padding: var(--sp-1);
  margin: 0 auto var(--sp-8);
  width: fit-content;
}

.tier-toggle__btn {
  padding: var(--sp-3) var(--sp-6);
  border-radius: var(--radius-lg);
  font-size: var(--fs-sm);
  font-weight: 600;
  color: var(--color-text-secondary);
  transition: all var(--t-base);
  white-space: nowrap;
}

.tier-toggle__btn.active {
  background: var(--color-primary-light);
  color: white;
  box-shadow: var(--shadow-md);
}

.tier-toggle__btn:not(.active):hover {
  color: var(--color-text);
  background: rgba(0,0,0,0.04);
}

/* Search / Filter */
.customize-controls {
  display: flex;
  gap: var(--sp-3);
  margin-bottom: var(--sp-6);
  flex-wrap: wrap;
}

.search-input {
  flex: 1;
  min-width: 200px;
  padding: var(--sp-3) var(--sp-5);
  padding-left: var(--sp-10);
  background: var(--color-bg-alt);
  border: 2px solid transparent;
  border-radius: var(--radius-xl);
  font-size: var(--fs-sm);
  transition: all var(--t-fast);
  position: relative;
}

.search-wrapper {
  position: relative;
  flex: 1;
  min-width: 200px;
}

.search-wrapper svg {
  position: absolute;
  left: var(--sp-4);
  top: 50%;
  transform: translateY(-50%);
  width: 18px;
  height: 18px;
  color: var(--color-text-light);
  pointer-events: none;
}

.search-input:focus {
  outline: none;
  border-color: var(--color-primary-light);
  background: white;
  box-shadow: 0 0 0 3px rgba(37,99,235,0.1);
}

.filter-select {
  padding: var(--sp-3) var(--sp-5);
  background: var(--color-bg-alt);
  border: 2px solid transparent;
  border-radius: var(--radius-xl);
  font-size: var(--fs-sm);
  font-weight: 500;
  color: var(--color-text);
  cursor: pointer;
  transition: all var(--t-fast);
  appearance: none;
  padding-right: var(--sp-10);
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right var(--sp-4) center;
}

.filter-select:focus {
  outline: none;
  border-color: var(--color-primary-light);
  box-shadow: 0 0 0 3px rgba(37,99,235,0.1);
}

/* Customize layout */
.customize-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-6);
}

/* Book grid */
.book-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--sp-4);
}

.book-card {
  background: var(--color-surface);
  border: 2px solid var(--color-border-light);
  border-radius: var(--radius-xl);
  overflow: hidden;
  transition: all var(--t-base);
  cursor: pointer;
  position: relative;
}

.book-card:hover {
  border-color: var(--color-primary-100);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.book-card.selected {
  border-color: var(--color-primary-light);
  background: var(--color-primary-50);
  box-shadow: 0 0 0 3px rgba(37,99,235,0.15);
}

.book-card.disabled {
  opacity: 0.5;
  pointer-events: none;
}

.book-card__cover {
  width: 100%;
  aspect-ratio: 3/4;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.5rem;
  color: rgba(255,255,255,0.8);
  position: relative;
}

.book-card__check {
  position: absolute;
  top: var(--sp-3);
  right: var(--sp-3);
  width: 28px;
  height: 28px;
  background: var(--color-primary-light);
  color: white;
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  transform: scale(0);
  transition: transform 200ms var(--ease-bounce);
}

.book-card.selected .book-card__check {
  transform: scale(1);
}

.book-card__info {
  padding: var(--sp-3) var(--sp-4);
}

.book-card__title {
  font-size: var(--fs-sm);
  font-weight: 600;
  color: var(--color-text);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.book-card__author {
  font-size: var(--fs-xs);
  color: var(--color-text-secondary);
}

/* Selection tray */
.selection-tray {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  box-shadow: 0 -4px 20px rgba(0,0,0,0.1);
  padding: var(--sp-4) var(--sp-5);
  z-index: var(--z-sticky);
  transform: translateY(100%);
  transition: transform var(--t-drawer);
}

.selection-tray.visible {
  transform: translateY(0);
}

.selection-tray__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--sp-3);
}

.selection-tray__counter {
  font-size: var(--fs-sm);
  font-weight: 600;
  color: var(--color-text);
}

.selection-tray__counter span {
  color: var(--color-primary-light);
}

.selection-tray__price {
  font-size: var(--fs-xl);
  font-weight: 800;
  color: var(--color-primary-light);
}

.selection-tray__books {
  display: flex;
  gap: var(--sp-2);
  overflow-x: auto;
  padding-bottom: var(--sp-2);
  margin-bottom: var(--sp-3);
  scrollbar-width: none;
}

.selection-tray__books::-webkit-scrollbar { display: none; }

.selection-tray__book-chip {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  padding: var(--sp-2) var(--sp-3);
  background: var(--color-primary-50);
  border-radius: var(--radius-full);
  font-size: var(--fs-xs);
  font-weight: 500;
  color: var(--color-primary);
  white-space: nowrap;
}

.selection-tray__book-chip button {
  width: 16px;
  height: 16px;
  border-radius: var(--radius-full);
  background: var(--color-primary-light);
  color: white;
  font-size: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
}


/* =====================================================
   11. CART DRAWER
   ===================================================== */
.cart-overlay {
  position: fixed;
  inset: 0;
  background: var(--color-overlay);
  z-index: var(--z-overlay);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--t-base);
}

.cart-overlay.open {
  opacity: 1;
  pointer-events: auto;
}

.cart-drawer {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: min(var(--drawer-width), 100vw);
  background: var(--color-surface);
  z-index: var(--z-drawer);
  transform: translateX(100%);
  transition: transform var(--t-drawer);
  display: flex;
  flex-direction: column;
  box-shadow: -8px 0 30px rgba(0,0,0,0.12);
}

.cart-drawer.open {
  transform: translateX(0);
}

.cart-drawer__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--sp-5) var(--sp-6);
  border-bottom: 1px solid var(--color-border-light);
}

.cart-drawer__title {
  font-size: var(--fs-xl);
  font-weight: 700;
}

.cart-drawer__close {
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-lg);
  transition: background var(--t-fast);
}

.cart-drawer__close:hover {
  background: var(--color-bg-alt);
}

.cart-drawer__items {
  flex: 1;
  overflow-y: auto;
  padding: var(--sp-4) var(--sp-6);
}

.cart-drawer__empty {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  gap: var(--sp-4);
  color: var(--color-text-light);
  text-align: center;
  padding: var(--sp-8);
}

.cart-drawer__empty-icon {
  font-size: 3rem;
  opacity: 0.5;
}

.cart-item {
  display: flex;
  gap: var(--sp-4);
  padding: var(--sp-4) 0;
  border-bottom: 1px solid var(--color-border-light);
  animation: slideIn 300ms var(--ease-out);
}

.cart-item:last-child { border-bottom: none; }

.cart-item__image {
  width: 72px;
  height: 72px;
  border-radius: var(--radius-lg);
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
}

.cart-item__details {
  flex: 1;
  min-width: 0;
}

.cart-item__name {
  font-size: var(--fs-sm);
  font-weight: 600;
  margin-bottom: var(--sp-1);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.cart-item__books {
  font-size: var(--fs-xs);
  color: var(--color-text-secondary);
  margin-bottom: var(--sp-2);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.cart-item__row {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.cart-item__qty {
  display: flex;
  align-items: center;
  gap: var(--sp-1);
}

.cart-item__qty-btn {
  width: 28px;
  height: 28px;
  border-radius: var(--radius-md);
  background: var(--color-bg-alt);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--fs-sm);
  font-weight: 600;
  transition: all var(--t-fast);
}

.cart-item__qty-btn:hover {
  background: var(--color-primary-light);
  color: white;
}

.cart-item__qty-num {
  width: 28px;
  text-align: center;
  font-size: var(--fs-sm);
  font-weight: 600;
}

.cart-item__price {
  font-size: var(--fs-sm);
  font-weight: 700;
  color: var(--color-primary);
}

.cart-item__remove {
  color: var(--color-text-light);
  font-size: var(--fs-xs);
  margin-top: var(--sp-2);
  transition: color var(--t-fast);
}

.cart-item__remove:hover { color: var(--color-error); }

.cart-drawer__footer {
  padding: var(--sp-5) var(--sp-6);
  border-top: 1px solid var(--color-border-light);
  background: var(--color-bg-alt);
}

.cart-drawer__subtotal {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--sp-4);
}

.cart-drawer__subtotal-label {
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
}

.cart-drawer__subtotal-value {
  font-size: var(--fs-xl);
  font-weight: 800;
  color: var(--color-text);
}

.cart-drawer__note {
  font-size: var(--fs-xs);
  color: var(--color-text-light);
  text-align: center;
  margin-top: var(--sp-3);
}


/* =====================================================
   12. CHECKOUT PAGE
   ===================================================== */
.checkout-page {
  padding: var(--sp-8) 0 var(--sp-16);
}

.checkout-page__header {
  margin-bottom: var(--sp-8);
}

.checkout-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-8);
}

/* Form card */
.form-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-2xl);
  padding: var(--sp-6);
  box-shadow: var(--shadow-sm);
}

.form-card__title {
  font-size: var(--fs-lg);
  font-weight: 700;
  margin-bottom: var(--sp-6);
  display: flex;
  align-items: center;
  gap: var(--sp-3);
}

.form-group {
  margin-bottom: var(--sp-5);
}

.form-label {
  display: block;
  font-size: var(--fs-sm);
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--sp-2);
}

.form-input,
.form-textarea {
  width: 100%;
  padding: var(--sp-3) var(--sp-4);
  background: var(--color-bg-alt);
  border: 2px solid transparent;
  border-radius: var(--radius-lg);
  font-size: var(--fs-base);
  color: var(--color-text);
  transition: all var(--t-fast);
}

.form-input:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--color-primary-light);
  background: white;
  box-shadow: 0 0 0 3px rgba(37,99,235,0.1);
}

.form-textarea {
  min-height: 100px;
  resize: vertical;
}

.form-error {
  display: none;
  font-size: var(--fs-xs);
  color: var(--color-error);
  margin-top: var(--sp-1);
}

.form-group--error .form-input,
.form-group--error .form-textarea {
  border-color: var(--color-error);
  background: var(--color-error-bg);
}

.form-group--error .form-error {
  display: block;
}

/* Delivery zone */
.zone-options {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--sp-4);
}

.zone-card {
  padding: var(--sp-5);
  background: var(--color-bg-alt);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-xl);
  text-align: center;
  cursor: pointer;
  transition: all var(--t-base);
}

.zone-card:hover {
  border-color: var(--color-primary-100);
  background: white;
}

.zone-card.selected {
  border-color: var(--color-primary-light);
  background: var(--color-primary-50);
  box-shadow: 0 0 0 3px rgba(37,99,235,0.12);
}

.zone-card__name {
  font-size: var(--fs-sm);
  font-weight: 600;
  margin-bottom: var(--sp-1);
}

.zone-card__price {
  font-size: var(--fs-lg);
  font-weight: 800;
  color: var(--color-primary-light);
}

/* Payment method */
.payment-card {
  display: flex;
  align-items: center;
  gap: var(--sp-4);
  padding: var(--sp-5);
  background: var(--color-bg-alt);
  border-radius: var(--radius-xl);
  border: 2px solid var(--color-success);
}

.payment-card__icon {
  width: 48px;
  height: 48px;
  background: var(--color-success-bg);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--fs-xl);
}

.payment-card__label {
  font-weight: 600;
}

.payment-card__sublabel {
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
}

/* Order summary (checkout sidebar) */
.order-summary {
  position: sticky;
  top: calc(var(--header-height) + var(--sp-6));
}

.order-summary__items {
  margin-bottom: var(--sp-6);
}

.order-summary__item {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  padding: var(--sp-3) 0;
  border-bottom: 1px solid var(--color-border-light);
  font-size: var(--fs-sm);
}

.order-summary__item:last-child { border-bottom: none; }

.order-summary__item-name {
  flex: 1;
  margin-right: var(--sp-4);
}

.order-summary__item-qty {
  color: var(--color-text-secondary);
  font-size: var(--fs-xs);
}

.order-summary__item-price {
  font-weight: 600;
  white-space: nowrap;
}

.order-summary__divider {
  height: 1px;
  background: var(--color-border);
  margin: var(--sp-4) 0;
}

.order-summary__row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--sp-2) 0;
  font-size: var(--fs-sm);
}

.order-summary__row--total {
  font-size: var(--fs-xl);
  font-weight: 800;
  padding: var(--sp-4) 0;
  border-top: 2px solid var(--color-text);
  margin-top: var(--sp-2);
}

.order-error {
  display: none;
  padding: var(--sp-4);
  background: var(--color-error-bg);
  border: 1px solid rgba(239,68,68,0.2);
  border-radius: var(--radius-lg);
  color: var(--color-error);
  font-size: var(--fs-sm);
  margin-top: var(--sp-4);
  text-align: center;
}

.order-error.visible { display: block; }


/* =====================================================
   13. GIFT BANNER
   ===================================================== */
.gift-banner {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: var(--z-modal);
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-overlay);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--t-base);
}

.gift-banner.visible {
  opacity: 1;
  pointer-events: auto;
}

.gift-banner__card {
  position: relative;
  background: transparent;
  border-radius: var(--radius-2xl);
  padding: 0;
  text-align: center;
  max-width: 620px;
  width: calc(100% - var(--sp-10));
  box-shadow: var(--shadow-2xl);
  transform: scale(0.9) translateY(20px);
  transition: transform var(--t-slow);
}

.gift-banner.visible .gift-banner__card {
  transform: scale(1) translateY(0);
}

.gift-banner__image {
  width: 100%;
  height: auto;
  border-radius: var(--radius-2xl);
  display: block;
  box-shadow: var(--shadow-2xl);
}

.gift-banner__close {
  position: absolute;
  top: var(--sp-4);
  right: var(--sp-4);
  width: 36px;
  height: 36px;
  border-radius: var(--radius-full);
  background: rgba(15, 23, 42, 0.55);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  cursor: pointer;
  z-index: 10;
  transition: all var(--t-fast);
  box-shadow: var(--shadow-sm);
}

.gift-banner__close:hover {
  background: rgba(15, 23, 42, 0.85);
  transform: scale(1.05);
}


/* =====================================================
   14. THANK YOU PAGE
   ===================================================== */
.thankyou-page {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - var(--header-height));
  padding: var(--sp-8) var(--sp-5);
}

.thankyou-card {
  max-width: 560px;
  width: 100%;
  text-align: center;
  animation: fadeInUp 600ms var(--ease-out);
}

.thankyou-card__icon {
  width: 100px;
  height: 100px;
  margin: 0 auto var(--sp-6);
  background: var(--color-success-bg);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3rem;
  animation: successPop 600ms 200ms var(--ease-bounce) both;
}

.thankyou-card__title {
  font-size: var(--fs-3xl);
  font-weight: 800;
  margin-bottom: var(--sp-3);
}

.thankyou-card__message {
  font-size: var(--fs-base);
  color: var(--color-text-secondary);
  margin-bottom: var(--sp-8);
  line-height: var(--lh-relaxed);
}

.thankyou-card__order-id {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  padding: var(--sp-3) var(--sp-5);
  background: var(--color-bg-alt);
  border-radius: var(--radius-full);
  font-size: var(--fs-sm);
  font-weight: 600;
  margin-bottom: var(--sp-8);
  color: var(--color-primary);
}

.thankyou-summary {
  background: var(--color-bg-alt);
  border-radius: var(--radius-2xl);
  padding: var(--sp-6);
  margin-bottom: var(--sp-8);
  text-align: left;
}

.thankyou-summary__title {
  font-size: var(--fs-sm);
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--color-text-light);
  margin-bottom: var(--sp-4);
}

.thankyou-summary__row {
  display: flex;
  justify-content: space-between;
  padding: var(--sp-2) 0;
  font-size: var(--fs-sm);
}

.thankyou-summary__row--total {
  font-weight: 700;
  font-size: var(--fs-base);
  border-top: 1px solid var(--color-border);
  margin-top: var(--sp-2);
  padding-top: var(--sp-3);
}

.thankyou-card__reassurance {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  padding: var(--sp-4) var(--sp-5);
  background: var(--color-success-bg);
  border-radius: var(--radius-xl);
  font-size: var(--fs-sm);
  color: var(--color-success);
  font-weight: 500;
  margin-bottom: var(--sp-8);
  justify-content: center;
}


/* =====================================================
   15. MODAL / LIGHTBOX
   ===================================================== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.85);
  z-index: var(--z-modal);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--t-base);
  padding: var(--sp-5);
}

.modal-overlay.open {
  opacity: 1;
  pointer-events: auto;
}

.modal {
  background: white;
  border-radius: var(--radius-2xl);
  max-width: 720px;
  width: 100%;
  max-height: 85vh;
  overflow-y: auto;
  transform: scale(0.95) translateY(16px);
  transition: transform var(--t-slow);
  box-shadow: var(--shadow-2xl);
}

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

.modal__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--sp-5) var(--sp-6);
  border-bottom: 1px solid var(--color-border-light);
  position: sticky;
  top: 0;
  background: white;
  border-radius: var(--radius-2xl) var(--radius-2xl) 0 0;
  z-index: 1;
}

.modal__title {
  font-size: var(--fs-lg);
  font-weight: 700;
}

.modal__close {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background var(--t-fast);
}

.modal__close:hover {
  background: var(--color-bg-alt);
}

.modal__body {
  padding: var(--sp-6);
}

.modal__body p {
  color: var(--color-text-secondary);
  margin-bottom: var(--sp-4);
  line-height: var(--lh-relaxed);
}

.quality-placeholder {
  background: var(--color-bg-alt);
  border-radius: var(--radius-xl);
  padding: var(--sp-10);
  text-align: center;
  color: var(--color-text-light);
}

.quality-placeholder__icon {
  font-size: 3rem;
  margin-bottom: var(--sp-4);
}


/* =====================================================
   16. FOOTER
   ===================================================== */
.footer {
  background: var(--color-bg-dark);
  color: rgba(255,255,255,0.7);
  padding: var(--sp-12) 0 var(--sp-8);
}

.footer__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--sp-8);
  margin-bottom: var(--sp-10);
}

.footer__brand {
  max-width: 300px;
}

.footer__logo {
  margin-bottom: var(--sp-3);
}

.footer__logo-img {
  height: 52px;
  width: auto;
  display: block;
  filter: brightness(0) invert(1);
}

.footer__desc {
  font-size: var(--fs-sm);
  line-height: var(--lh-relaxed);
}

.footer__col-title {
  font-size: var(--fs-sm);
  font-weight: 700;
  color: white;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: var(--sp-4);
}

.footer__links a {
  display: block;
  padding: var(--sp-2) 0;
  font-size: var(--fs-sm);
  transition: color var(--t-fast);
}

.footer__links a:hover {
  color: white;
}

.footer__bottom {
  padding-top: var(--sp-6);
  border-top: 1px solid rgba(255,255,255,0.1);
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
  align-items: center;
  font-size: var(--fs-sm);
}


/* =====================================================
   17. TOAST / NOTIFICATIONS
   ===================================================== */
.toast-container {
  position: fixed;
  bottom: var(--sp-6);
  left: 50%;
  transform: translateX(-50%);
  z-index: var(--z-toast);
  display: flex;
  flex-direction: column-reverse;
  gap: var(--sp-3);
  pointer-events: none;
}

.toast {
  background: var(--color-bg-dark);
  color: white;
  padding: var(--sp-3) var(--sp-6);
  border-radius: var(--radius-xl);
  font-size: var(--fs-sm);
  font-weight: 500;
  box-shadow: var(--shadow-xl);
  animation: toastIn 400ms var(--ease-bounce), toastOut 300ms 2500ms var(--ease-out) forwards;
  pointer-events: auto;
  white-space: nowrap;
}

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


/* =====================================================
   18. ANIMATIONS
   ===================================================== */
@keyframes heroFloat {
  0%, 100% { transform: translateY(0) scale(1); }
  50% { transform: translateY(-30px) scale(1.05); }
}

@keyframes badgePop {
  0% { transform: scale(1); }
  50% { transform: scale(1.4); }
  100% { transform: scale(1); }
}

@keyframes slideIn {
  from { opacity: 0; transform: translateX(16px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

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

@keyframes giftBounce {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-12px); }
}

@keyframes toastIn {
  from { opacity: 0; transform: translateY(16px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes toastOut {
  from { opacity: 1; transform: translateY(0); }
  to { opacity: 0; transform: translateY(-8px); }
}

@keyframes shimmer {
  0% { background-position: -200% 0; }
  100% { background-position: 200% 0; }
}

.animate-in {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 600ms var(--ease-out), transform 600ms var(--ease-out);
}

.animate-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Loading skeleton */
.skeleton {
  background: linear-gradient(90deg, var(--color-bg-alt) 25%, #e2e8f0 50%, var(--color-bg-alt) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: var(--radius-md);
}


/* =====================================================
   19. RESPONSIVE — TABLET (≥768px)
   ===================================================== */
@media (min-width: 768px) {
  :root {
    --header-height: 80px;
  }

  .hero__inner {
    grid-template-columns: 1fr 1fr;
    gap: var(--sp-10);
    align-items: center;
  }
  .hero__content {
    padding-top: var(--sp-2);
    padding-bottom: var(--sp-10);
  }
  .hero__title { font-size: var(--fs-5xl); }

  .products-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .header__nav { display: flex; }
  .header__menu-btn { display: none; }
  .header__quality-btn { display: flex; }

  .product-detail__grid {
    grid-template-columns: 1fr 1fr;
    align-items: flex-start;
  }

  .book-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .checkout-grid {
    grid-template-columns: 1fr 380px;
    align-items: flex-start;
  }

  .footer__grid {
    grid-template-columns: 2fr 1fr 1fr;
  }

  .footer__bottom {
    flex-direction: row;
    justify-content: space-between;
  }

  /* Selection tray becomes sidebar */
  .selection-tray {
    position: sticky;
    top: calc(var(--header-height) + var(--sp-6));
    bottom: auto;
    left: auto;
    right: auto;
    transform: none;
    border-top: none;
    box-shadow: var(--shadow-md);
    border-radius: var(--radius-2xl);
    border: 1px solid var(--color-border-light);
  }

  .customize-layout {
    grid-template-columns: 1fr 320px;
    align-items: flex-start;
  }
}


/* =====================================================
   20. RESPONSIVE — DESKTOP (≥1024px)
   ===================================================== */
@media (min-width: 1024px) {
  .hero__title { font-size: var(--fs-6xl); }

  .products-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .book-grid {
    grid-template-columns: repeat(5, 1fr);
  }

  .customize-page .container {
    max-width: 1440px;
  }

  .section-title { font-size: var(--fs-3xl); }
}


/* =====================================================
   21. SCROLLBAR
   ===================================================== */
::-webkit-scrollbar {
  width: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-text-light);
}


/* =====================================================
   21. REVIEWS & RATINGS SECTION
   ===================================================== */
.reviews-section {
  padding: var(--sp-12) 0;
  border-top: 1px solid var(--color-border);
  background: var(--color-bg);
}

.reviews {
  max-width: 900px;
  margin: 0 auto;
  padding: 0 var(--sp-4);
}

.reviews__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--sp-8);
  flex-wrap: wrap;
  gap: var(--sp-4);
  border-bottom: 2px solid var(--color-border-light);
  padding-bottom: var(--sp-4);
}

.reviews__title {
  font-size: var(--fs-2xl);
  font-weight: 800;
  color: var(--color-text);
  margin: 0;
}

.reviews__write-trigger {
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
  display: flex;
  align-items: center;
  gap: var(--sp-4);
}

.reviews__write-trigger span {
  font-weight: 500;
}

.reviews__summary {
  display: flex;
  background: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-xl);
  padding: var(--sp-8);
  margin-bottom: var(--sp-10);
  align-items: center;
  gap: var(--sp-12);
  box-shadow: var(--shadow-sm);
}

.reviews__summary-left {
  text-align: center;
  min-width: 180px;
  border-right: 1px solid var(--color-border-light);
  padding-right: var(--sp-8);
}

@media (max-width: 768px) {
  .reviews__summary {
    flex-direction: column;
    align-items: stretch;
    gap: var(--sp-6);
  }
  .reviews__summary-left {
    border-right: none;
    border-bottom: 1px solid var(--color-border-light);
    padding-right: 0;
    padding-bottom: var(--sp-6);
  }
}

.reviews__avg-score {
  font-size: 3.5rem;
  font-weight: 900;
  color: var(--color-text);
  line-height: 1;
  margin-bottom: var(--sp-2);
  letter-spacing: -0.02em;
}

.reviews__avg-stars {
  display: flex;
  justify-content: center;
  gap: 3px;
  margin-bottom: var(--sp-3);
}

.reviews__count {
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
  font-weight: 600;
}

.reviews__summary-right {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: var(--sp-2.5);
}

.reviews__bar-row {
  display: flex;
  align-items: center;
  gap: var(--sp-4);
  font-size: var(--fs-xs);
}

.reviews__bar-label {
  display: inline-flex;
  gap: 1px;
  width: 60px;
  justify-content: flex-end;
}

.reviews__bar-track {
  flex: 1;
  height: 8px;
  background: var(--color-bg-alt);
  border-radius: var(--radius-full);
  overflow: hidden;
  position: relative;
}

.reviews__bar-fill {
  height: 100%;
  background: #f59e0b;
  border-radius: var(--radius-full);
}

.reviews__bar-count {
  width: 28px;
  text-align: left;
  color: var(--color-text-secondary);
  font-weight: 600;
}

.reviews__controls {
  display: flex;
  justify-content: flex-end;
  border-bottom: 1px solid var(--color-border-light);
  padding-bottom: var(--sp-3);
  margin-bottom: var(--sp-8);
}

.reviews__sort {
  display: flex;
  align-items: center;
  gap: var(--sp-2);
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
  font-weight: 500;
}

.reviews__sort select {
  border: 1px solid var(--color-border);
  background: white;
  padding: var(--sp-1.5) var(--sp-4);
  border-radius: var(--radius-md);
  font-weight: 600;
  color: var(--color-text);
  outline: none;
  cursor: pointer;
  font-size: var(--fs-sm);
  transition: border-color var(--t-fast);
}

.reviews__sort select:focus {
  border-color: var(--color-primary-light);
}

.reviews__list {
  display: flex;
  flex-direction: column;
  gap: var(--sp-8);
}

.review-card {
  padding-bottom: var(--sp-8);
  border-bottom: 1px solid var(--color-border-light);
  animation: fadeIn 0.4s ease-out;
}

.review-card:last-child {
  border-bottom: none;
}

.review-card--new {
  background: var(--color-primary-50);
  border-radius: var(--radius-lg);
  padding: var(--sp-5);
  border: 1px dashed var(--color-primary-light);
}

.review-card__header {
  display: flex;
  align-items: flex-start;
  gap: var(--sp-4);
  margin-bottom: var(--sp-3);
}

.review-card__avatar {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-full);
  background: var(--color-primary-100);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: var(--fs-lg);
  flex-shrink: 0;
  box-shadow: inset 0 2px 4px rgba(0,0,0,0.05);
}

.review-card__meta {
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
  line-height: var(--lh-tight);
}

.review-card__name {
  color: var(--color-text);
}

.review-card__name strong {
  font-weight: 700;
  color: var(--color-text);
}

.review-card__date {
  font-weight: 500;
  color: var(--color-text-light);
}

.review-card__subheader {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  margin-top: var(--sp-1.5);
  flex-wrap: wrap;
}

.review-card__stars {
  display: flex;
  gap: 2px;
}

.review-card__verified {
  font-size: var(--fs-xs);
  color: var(--color-success);
  font-weight: 700;
  display: inline-flex;
  align-items: center;
  gap: var(--sp-1);
}

.review-card__verified--new {
  color: var(--color-primary-light);
}

.review-card__text {
  font-size: var(--fs-sm);
  line-height: var(--lh-relaxed);
  color: var(--color-text);
  margin: 0 0 var(--sp-4) 0;
  font-weight: 400;
  padding-left: 0;
}

@media (min-width: 600px) {
  .review-card__text {
    padding-left: 60px; /* Aligns body text beautifully under header info, bypassing avatar */
  }
  .review-card__helpful {
    padding-left: 60px;
  }
}

.review-card__helpful {
  font-size: var(--fs-xs);
  color: var(--color-text-secondary);
  display: flex;
  align-items: center;
  gap: var(--sp-4);
  flex-wrap: wrap;
}

.review-card__helpful span {
  font-weight: 500;
}

.review-card__helpful-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-1.5);
  background: white;
  border: 1px solid var(--color-border);
  padding: var(--sp-1.5) var(--sp-4);
  border-radius: var(--radius-md);
  font-size: var(--fs-2xs);
  font-weight: 600;
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--t-fast);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.review-card__helpful-btn:hover {
  background: var(--color-bg-alt);
  border-color: var(--color-text-light);
  color: var(--color-text);
}

.review-card__helpful-btn:disabled {
  background: var(--color-bg-alt);
  color: var(--color-text-light);
  border-color: var(--color-border-light);
  cursor: default;
}

/* Write feedback styling */
.write-review-section {
  padding: var(--sp-16) 0 var(--sp-24);
  background: var(--color-bg-alt);
  border-top: 1px solid var(--color-border);
}

.write-review {
  max-width: 600px;
  margin: 0 auto;
  background: var(--color-surface);
  border-radius: var(--radius-2xl);
  padding: var(--sp-8) var(--sp-10);
  box-shadow: var(--shadow-lg);
}

@media (max-width: 480px) {
  .write-review {
    padding: var(--sp-6) var(--sp-5);
  }
}

.write-review__title {
  font-size: var(--fs-xl);
  font-weight: 800;
  color: var(--color-text);
  margin: 0 0 var(--sp-1) 0;
  letter-spacing: -0.01em;
}

.write-review__subtitle {
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
  margin: 0 0 var(--sp-6) 0;
  line-height: var(--lh-base);
}

.write-review__form {
  display: flex;
  flex-direction: column;
  gap: var(--sp-5);
}

.write-review__field {
  display: flex;
  flex-direction: column;
  gap: var(--sp-2);
}

.write-review__label {
  font-size: var(--fs-sm);
  font-weight: 700;
  color: var(--color-text);
}

.write-review__stars {
  display: flex;
  align-items: center;
  gap: var(--sp-1.5);
  flex-wrap: wrap;
}

.write-review__star-btn {
  background: transparent;
  border: none;
  cursor: pointer;
  padding: 0;
  transition: transform var(--t-fast);
}

.write-review__star-btn:hover {
  transform: scale(1.2);
}

.write-review__star-text {
  font-size: var(--fs-sm);
  font-weight: 700;
  color: var(--color-text-light);
  margin-left: var(--sp-3);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.write-review__input,
.write-review__textarea {
  padding: var(--sp-3.5) var(--sp-4.5);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  font-family: inherit;
  font-size: var(--fs-sm);
  color: var(--color-text);
  outline: none;
  transition: all var(--t-fast);
  background: var(--color-bg);
}

.write-review__input:focus,
.write-review__textarea:focus {
  border-color: var(--color-primary-light);
  box-shadow: 0 0 0 4px rgba(59,108,245,0.1);
  background: white;
}

.write-review__submit {
  align-self: flex-start;
  margin-top: var(--sp-2);
  min-width: 160px;
}

@media (max-width: 480px) {
  .write-review__submit {
    align-self: stretch;
  }
}

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


/* =====================================================
   22. LOADING OVERLAY
   ===================================================== */
.loading-overlay {
  position: fixed;
  inset: 0;
  background: var(--color-overlay);
  z-index: var(--z-modal);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--t-base);
}

.loading-overlay.visible {
  opacity: 1;
  pointer-events: auto;
}

.loading-card {
  background: white;
  border-radius: var(--radius-2xl);
  padding: var(--sp-8) var(--sp-6);
  text-align: center;
  max-width: 400px;
  width: calc(100% - var(--sp-10));
  box-shadow: var(--shadow-2xl);
  transform: scale(0.9) translateY(20px);
  transition: transform var(--t-slow);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--sp-4);
}

.loading-overlay.visible .loading-card {
  transform: scale(1) translateY(0);
}

.loading-card__spinner {
  width: 48px;
  height: 48px;
  border: 4px solid var(--color-border);
  border-top-color: var(--color-primary-light);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

.loading-card__title {
  font-size: var(--fs-xl);
  font-weight: 800;
  color: var(--color-text);
  margin: 0;
}

.loading-card__subtitle {
  font-size: var(--fs-sm);
  color: var(--color-text-secondary);
  line-height: var(--lh-relaxed);
  margin: 0;
}

.progress-bar-container {
  width: 100%;
  height: 8px;
  background: var(--color-bg-alt);
  border-radius: var(--radius-full);
  overflow: hidden;
  margin-top: var(--sp-2);
  border: 1px solid var(--color-border-light);
}

.progress-bar {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--color-primary-light) 0%, var(--color-primary) 100%);
  border-radius: var(--radius-full);
  transition: width 150ms ease-out;
}

.progress-percentage {
  font-size: var(--fs-xs);
  font-weight: 700;
  color: var(--color-primary);
}


/* =====================================================
   23. PRINT
   ===================================================== */
@media print {
  .header, .footer, .cart-drawer, .cart-overlay,
  .gift-banner, .toast-container, .loading-overlay { display: none !important; }
  .page-content { padding-top: 0; }
}

/* =====================================================
   24. VARIANT SELECTOR STYLES
   ===================================================== */
.variant-selector-section {
  margin: var(--sp-4) 0;
}

.variant-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: var(--sp-3);
  margin-top: var(--sp-2);
}

.variant-card {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: var(--sp-3) var(--sp-4);
  background: white;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-xl);
  cursor: pointer;
  transition: all var(--t-fast);
  text-align: left;
  position: relative;
}

.variant-card:hover {
  border-color: var(--color-primary-light);
  background: var(--color-bg-alt);
  transform: translateY(-2px);
}

.variant-card.selected {
  border-color: var(--color-primary);
  background: rgba(59, 108, 245, 0.05);
  box-shadow: 0 0 0 3px rgba(59, 108, 245, 0.15);
}

.variant-card__header {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.variant-card__name {
  font-size: var(--fs-sm);
  font-weight: 700;
  color: var(--color-text);
}

.variant-card__price {
  font-size: var(--fs-base);
  font-weight: 800;
  color: var(--color-primary);
}

.variant-card__badge {
  display: inline-block;
  margin-top: var(--sp-2);
  font-size: 11px;
  font-weight: 700;
  padding: 2px 8px;
  background: var(--color-primary);
  color: white;
  border-radius: var(--radius-full);
  align-self: flex-start;
}

/* ---- Product Card Variant Prices Showcase ---- */
.product-card__variants-showcase {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--sp-2);
  margin-bottom: var(--sp-4);
  background: var(--color-bg-alt);
  padding: var(--sp-2);
  border-radius: var(--radius-xl);
  border: 1px solid var(--color-border-light);
}

.variant-price-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--sp-2) 4px;
  background: white;
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  text-align: center;
  transition: all var(--t-fast);
}

.variant-price-item--combo {
  border-color: var(--color-primary);
  background: rgba(59, 108, 245, 0.08);
}

.variant-price-item__label {
  font-size: 10px;
  font-weight: 700;
  color: var(--color-text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.03em;
  white-space: nowrap;
  margin-bottom: 2px;
}

.variant-price-item--combo .variant-price-item__label {
  color: var(--color-primary);
}

.variant-price-item__val {
  font-size: var(--fs-sm);
  font-weight: 800;
  color: var(--color-text);
}

.variant-price-item--combo .variant-price-item__val {
  color: var(--color-primary);
}