/* ==========================================================================
   ENGINEER KHALID MAGSI - AUTHOR PORTFOLIO & E-COMMERCE DESIGN SYSTEM
   Theme: Obsidian Slate & Technical Blueprint (Dark Premium Minimalist)
   ========================================================================== */

:root {
  /* Color Palette */
  --bg-dark: #0A0A0A;
  --bg-card: #141414;
  --bg-card-hover: #1C1C1C;
  --bg-glass: rgba(20, 20, 20, 0.88);
  --bg-glass-border: rgba(255, 255, 255, 0.08);

  --text-main: #F8FAFC;
  --text-muted: #94A3B8;
  --text-dim: #64748B;

  --accent-cyan: #C5A059;
  --accent-cyan-glow: rgba(197, 160, 89, 0.3);
  --accent-amber: #B87333;
  --accent-blue: #8B7355;
  --accent-emerald: #556B2F;

  --border-light: rgba(255, 255, 255, 0.08);
  --border-active: rgba(197, 160, 89, 0.5);

  /* Typography */
  --font-body: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-heading: 'Space Grotesk', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  /* Radius & Shadows */
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-pill: 9999px;

  --shadow-card: 0 12px 32px -10px rgba(0, 0, 0, 0.6);
  --shadow-glow: 0 0 25px rgba(14, 165, 233, 0.25);

  --transition-fast: 0.2s cubic-bezier(0.16, 1, 0.3, 1);
  --transition-smooth: 0.35s cubic-bezier(0.16, 1, 0.3, 1);
}

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

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

body {
  background-color: var(--bg-dark);
  color: var(--text-main);
  font-family: var(--font-body);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  max-width: 100vw;
}

/* Technical Grid Pattern Background */
body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background-image: 
    radial-gradient(rgba(14, 165, 233, 0.08) 1px, transparent 1px),
    linear-gradient(to right, rgba(255, 255, 255, 0.02) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(255, 255, 255, 0.02) 1px, transparent 1px);
  background-size: 40px 40px, 80px 80px, 80px 80px;
  pointer-events: none;
  z-index: -1;
}

/* Utility Containers */
.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 24px;
}

.section-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  background: rgba(14, 165, 233, 0.1);
  border: 1px solid rgba(14, 165, 233, 0.3);
  border-radius: var(--radius-pill);
  color: var(--accent-cyan);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 16px;
}

.section-title {
  font-family: var(--font-heading);
  font-size: 2.5rem;
  font-weight: 700;
  letter-spacing: -0.5px;
  color: var(--text-main);
  margin-bottom: 16px;
}

.section-title span {
  background: linear-gradient(135deg, var(--text-main) 30%, var(--accent-cyan) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.section-subtitle {
  color: var(--text-muted);
  font-size: 1.1rem;
  max-width: 680px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 22px;
  border-radius: var(--radius-md);
  font-family: var(--font-heading);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  border: 1px solid transparent;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent-cyan), #0284C7);
  color: #FFFFFF;
  box-shadow: 0 4px 20px var(--accent-cyan-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(14, 165, 233, 0.4);
  background: linear-gradient(135deg, #38BDF8, #0EA5E9);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-main);
  border-color: var(--border-light);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.2);
  transform: translateY(-2px);
}

.btn-outline {
  background: transparent;
  color: var(--accent-cyan);
  border-color: var(--accent-cyan);
}

.btn-outline:hover {
  background: rgba(14, 165, 233, 0.12);
  box-shadow: 0 0 15px var(--accent-cyan-glow);
}

.btn-amber {
  background: linear-gradient(135deg, var(--accent-amber), #D97706);
  color: #0F172A;
  font-weight: 700;
}

.btn-amber:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(245, 158, 11, 0.4);
}

.btn-emerald {
  background: linear-gradient(135deg, var(--accent-emerald), #059669);
  color: #FFFFFF;
  font-weight: 700;
}

.btn-emerald:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(16, 185, 129, 0.4);
}

.btn-sm {
  padding: 8px 14px;
  font-size: 0.82rem;
}

.btn-icon {
  padding: 8px 12px;
}

/* Header & Nav */
.site-header {
  position: sticky;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: var(--bg-glass);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-light);
}

.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 80px;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: var(--text-main);
}

.brand-icon {
  width: 42px;
  height: 42px;
  background: linear-gradient(135deg, var(--accent-cyan), #0284C7);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-weight: 800;
  font-size: 1.2rem;
  color: #FFF;
  box-shadow: 0 0 15px var(--accent-cyan-glow);
}

.brand-name {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.15rem;
  letter-spacing: -0.3px;
}

.brand-title {
  font-size: 0.72rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  letter-spacing: 0.5px;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

.nav-link {
  text-decoration: none;
  color: var(--text-muted);
  font-family: var(--font-heading);
  font-weight: 500;
  font-size: 0.95rem;
  transition: color var(--transition-fast);
  position: relative;
  padding: 6px 0;
}

.nav-link:hover, .nav-link.active {
  color: var(--accent-cyan);
}

.nav-link.active::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  height: 2px;
  background: var(--accent-cyan);
  border-radius: 2px;
  box-shadow: 0 0 8px var(--accent-cyan);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

.mobile-toggle {
  display: none;
  background: none;
  border: none;
  color: var(--text-main);
  font-size: 1.5rem;
  cursor: pointer;
}

/* Hero Section */
.hero-section {
  padding: 100px 0 80px;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 60px;
  align-items: center;
}

.hero-headline {
  font-family: var(--font-heading);
  font-size: 3.5rem;
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -1px;
  margin-bottom: 20px;
}

.hero-headline span {
  background: linear-gradient(135deg, #FFF 0%, var(--accent-cyan) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 1.2rem;
  color: var(--text-muted);
  margin-bottom: 36px;
  line-height: 1.7;
}

.hero-ctas {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 48px;
}

.hero-stats {
  display: flex;
  align-items: center;
  gap: 40px;
  padding-top: 32px;
  border-top: 1px solid var(--border-light);
}

.stat-value {
  font-family: var(--font-heading);
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent-cyan);
}

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

/* Hero Visual Card */
.hero-visual {
  display: flex;
  justify-content: center;
}

.hero-book-card {
  width: 100%;
  max-width: 380px;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-card);
  position: relative;
  transform: rotate(-2deg);
  transition: transform var(--transition-smooth);
}

.hero-book-card:hover {
  transform: rotate(0deg) scale(1.02);
}

.hero-book-img {
  width: 100%;
  border-radius: var(--radius-md);
  box-shadow: 0 15px 35px rgba(0, 0, 0, 0.6);
  display: block;
}

.floating-badge {
  position: absolute;
  bottom: -20px;
  right: -20px;
  background: var(--bg-card);
  border: 1px solid var(--accent-cyan);
  padding: 12px 20px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  gap: 12px;
  box-shadow: var(--shadow-glow);
}

.badge-icon {
  color: var(--accent-amber);
  font-size: 1.4rem;
}

.badge-text strong {
  display: block;
  font-size: 0.9rem;
}

.badge-text span {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Books Grid Section (22 Books) */
.books-section {
  padding: 90px 0;
  background: rgba(15, 23, 42, 0.4);
  border-top: 1px solid var(--border-light);
  border-bottom: 1px solid var(--border-light);
}

.books-header {
  text-align: center;
  margin-bottom: 40px;
}

.controls-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 40px;
  flex-wrap: wrap;
}

.filter-pills {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.filter-pill {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--border-light);
  color: var(--text-muted);
  padding: 8px 18px;
  border-radius: var(--radius-pill);
  font-size: 0.88rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.filter-pill:hover, .filter-pill.active {
  background: rgba(14, 165, 233, 0.15);
  border-color: var(--accent-cyan);
  color: var(--text-main);
}

.search-box {
  position: relative;
  min-width: 280px;
}

.search-input {
  width: 100%;
  padding: 10px 16px 10px 42px;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-pill);
  color: var(--text-main);
  font-family: var(--font-body);
  font-size: 0.9rem;
  outline: none;
  transition: border-color var(--transition-fast);
}

.search-input:focus {
  border-color: var(--accent-cyan);
  box-shadow: 0 0 12px var(--accent-cyan-glow);
}

.search-icon {
  position: absolute;
  left: 16px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
}

/* 4-Column Responsive Grid */
.books-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 28px;
  align-items: stretch;
}

/* Enhanced Book Card Item */
.book-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 18px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  height: 100%;
  transition: all var(--transition-smooth);
  position: relative;
}

.book-card:hover {
  transform: translateY(-6px);
  border-color: var(--border-active);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.6), var(--shadow-glow);
}

.book-cover-wrap {
  width: 100%;
  height: 260px;
  background: var(--bg-dark);
  border-radius: var(--radius-md);
  overflow: hidden;
  margin-bottom: 14px;
  position: relative;
  flex-shrink: 0;
}

.book-cover-img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  background: var(--bg-card);
  transition: transform var(--transition-smooth);
}

.book-card:hover .book-cover-img {
  transform: scale(1.04);
}

.author-overlay {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  background: rgba(0, 0, 0, 0.7);
  color: var(--accent-cyan);
  font-family: var(--font-heading);
  font-size: 0.65rem;
  text-align: center;
  padding: 4px 2px;
  font-weight: 700;
  letter-spacing: 0.5px;
  backdrop-filter: blur(4px);
  z-index: 10;
}

.category-tag {
  font-size: 0.72rem;
  font-family: var(--font-mono);
  color: var(--accent-cyan);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 6px;
  display: flex;
  align-items: center;
  gap: 6px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.book-card-title {
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 700;
  line-height: 1.35;
  color: var(--text-main);
  margin-bottom: 8px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  height: 2.7em;
}

.book-card-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 14px;
}

.book-rating {
  color: var(--accent-amber);
  font-weight: 600;
}

/* Pricing Row */
.book-card-price-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
  padding-top: 10px;
  border-top: 1px solid var(--border-light);
}

.price-current {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--text-main);
}

.price-original {
  font-size: 0.82rem;
  color: var(--text-dim);
  text-decoration: line-through;
  margin-left: 6px;
}

/* Card Action Buttons Group (3 Buttons: Sample 5-Page, Buy Download, Details) */
.card-actions-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-top: auto;
}

.card-action-row {
  display: flex;
  gap: 6px;
}

.card-action-row .btn {
  flex: 1;
}

/* Single Product Section */
.single-product-section {
  padding: 90px 0;
  border-bottom: 1px solid var(--border-light);
}

.product-layout {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: 60px;
  align-items: start;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 40px;
  box-shadow: var(--shadow-card);
}

.main-book-cover {
  width: 100%;
  border-radius: var(--radius-md);
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.7);
  border: 1px solid var(--border-light);
}

.spec-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  background: rgba(7, 11, 20, 0.6);
  padding: 18px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-light);
  margin-top: 20px;
}

.spec-label {
  font-size: 0.75rem;
  color: var(--text-dim);
  text-transform: uppercase;
  font-family: var(--font-mono);
}

.spec-val {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-main);
}

.product-title {
  font-family: var(--font-heading);
  font-size: 2.2rem;
  font-weight: 700;
  line-height: 1.2;
}

.author-byline {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--accent-cyan);
  font-size: 1rem;
  font-weight: 600;
}

.author-avatar-sm {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  object-fit: cover;
  border: 1px solid var(--accent-cyan);
}

.product-description {
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1.7;
}

.highlights-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.highlights-list li {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: 0.92rem;
  color: var(--text-main);
}

.highlights-list li i {
  color: var(--accent-cyan);
  margin-top: 4px;
}

/* Sample Preview Trigger Box */
.sample-preview-box {
  background: rgba(7, 11, 20, 0.7);
  border: 1px dashed var(--accent-cyan);
  border-radius: var(--radius-md);
  padding: 20px;
  margin-top: 10px;
}

.sample-title {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 14px;
}

.sample-thumbnails {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
}

.sample-thumb-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  padding: 8px;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-align: center;
}

.sample-thumb-card:hover {
  border-color: var(--accent-cyan);
  transform: translateY(-2px);
  box-shadow: 0 5px 15px var(--accent-cyan-glow);
}

.sample-thumb-img {
  width: 100%;
  aspect-ratio: 3/4;
  background: #1E293B;
  border-radius: 4px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  color: var(--text-muted);
  gap: 4px;
}

.sample-thumb-img i {
  font-size: 1rem;
  color: var(--accent-cyan);
}

.sample-thumb-label {
  font-size: 0.7rem;
  color: var(--text-muted);
  margin-top: 4px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* Buy Action Box */
.buy-action-box {
  display: flex;
  align-items: center;
  gap: 20px;
  background: rgba(14, 165, 233, 0.08);
  border: 1px solid var(--border-active);
  padding: 20px;
  border-radius: var(--radius-md);
  margin-top: 10px;
}

.checkout-price {
  font-family: var(--font-heading);
  font-size: 2rem;
  font-weight: 800;
  color: var(--text-main);
}

.checkout-subtext {
  font-size: 0.75rem;
  color: var(--accent-cyan);
  font-family: var(--font-mono);
}

/* About Author & Classified Security Card */
.about-section {
  padding: 90px 0;
  background: var(--bg-dark);
}

.about-grid {
  display: grid;
  grid-template-columns: 0.85fr 1.15fr;
  gap: 50px;
  align-items: start;
}

.author-security-card {
  width: 100%;
}

.classified-badge-container {
  background: linear-gradient(145deg, #0F172A, #0B1120);
  border: 1px solid var(--accent-cyan);
  border-radius: var(--radius-lg);
  padding: 36px 24px;
  text-align: center;
  position: relative;
  box-shadow: 0 15px 40px rgba(0, 0, 0, 0.7), var(--shadow-glow);
  overflow: hidden;
}

.classified-badge-container::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, var(--accent-cyan), var(--accent-amber), var(--accent-emerald));
}

.classified-stamp {
  position: absolute;
  top: 20px;
  right: -30px;
  background: rgba(245, 158, 11, 0.2);
  border: 1px solid var(--accent-amber);
  color: var(--accent-amber);
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 700;
  padding: 4px 30px;
  transform: rotate(30deg);
  letter-spacing: 1px;
}

.author-avatar-large {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background: rgba(14, 165, 233, 0.12);
  border: 2px solid var(--accent-cyan);
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 20px;
  color: var(--accent-cyan);
  font-size: 3rem;
  box-shadow: 0 0 25px var(--accent-cyan-glow);
}

.author-badge-name {
  font-family: var(--font-heading);
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-main);
}

.author-badge-alias {
  font-family: var(--font-mono);
  color: var(--accent-amber);
  font-size: 0.9rem;
  margin-bottom: 20px;
  font-weight: 600;
}

.author-badge-meta {
  display: flex;
  flex-direction: column;
  gap: 10px;
  font-size: 0.85rem;
  color: var(--text-muted);
  text-align: left;
  background: rgba(7, 11, 20, 0.6);
  padding: 16px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-light);
  margin-bottom: 20px;
}

.author-badge-meta span {
  display: flex;
  align-items: center;
  gap: 8px;
}

.author-badge-meta i {
  color: var(--accent-cyan);
  width: 16px;
}

.author-badge-footer {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-dim);
  letter-spacing: 0.5px;
}

.author-bio {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.author-intro-title {
  font-size: 1.1rem;
  color: var(--text-main);
  line-height: 1.7;
}

.bio-detail-group {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  padding: 20px;
  border-radius: var(--radius-md);
}

.bio-subhead {
  font-family: var(--font-heading);
  font-size: 1rem;
  color: var(--accent-cyan);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.bio-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
  font-size: 0.92rem;
  color: var(--text-muted);
}

.bio-list li strong {
  color: var(--text-main);
}

/* Locked Book Overlay Styling */
.locked-overlay-badge {
  position: absolute;
  top: 12px;
  right: 12px;
  background: rgba(15, 23, 42, 0.9);
  border: 1px solid var(--accent-amber);
  color: var(--accent-amber);
  padding: 4px 10px;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 700;
}

/* Contact Section */
.contact-section {
  padding: 90px 0;
  background: rgba(15, 23, 42, 0.4);
  border-top: 1px solid var(--border-light);
}

.contact-grid {
  display: grid;
  grid-template-columns: 0.9fr 1.1fr;
  gap: 60px;
}

.contact-info-list {
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin-top: 24px;
}

.info-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  padding: 18px;
  border-radius: var(--radius-md);
}

.info-icon {
  width: 44px;
  height: 44px;
  background: rgba(14, 165, 233, 0.1);
  border-radius: var(--radius-sm);
  color: var(--accent-cyan);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
}

.contact-form {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  padding: 36px;
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.form-label {
  font-size: 0.85rem;
  font-family: var(--font-heading);
  font-weight: 600;
  color: var(--text-main);
}

.form-input, .form-textarea, .form-select {
  width: 100%;
  padding: 12px 16px;
  background: var(--bg-dark);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  color: var(--text-main);
  font-family: var(--font-body);
  font-size: 0.95rem;
  outline: none;
  transition: border-color var(--transition-fast);
}

.form-input:focus, .form-textarea:focus, .form-select:focus {
  border-color: var(--accent-cyan);
}

/* Footer */
.site-footer {
  background: #04070D;
  border-top: 1px solid var(--border-light);
  padding: 50px 0 30px;
  color: var(--text-muted);
}

.footer-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 30px;
  border-bottom: 1px solid var(--border-light);
  flex-wrap: wrap;
  gap: 20px;
}

.footer-links {
  display: flex;
  align-items: center;
  gap: 24px;
  list-style: none;
}

.footer-link {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  transition: color var(--transition-fast);
}

.footer-link:hover {
  color: var(--accent-cyan);
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 24px;
  font-size: 0.85rem;
}

/* Modals System */
.detail-modal-grid {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 32px;
  align-items: start;
}

.modal-buy-box {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(14, 165, 233, 0.1);
  padding: 16px 20px;
  border-radius: 12px;
  border: 1px solid var(--border-active);
}

.reader-toolbar-info {
  display: flex;
  align-items: center;
  gap: 10px;
}

.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(4, 7, 13, 0.88);
  backdrop-filter: blur(8px);
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-fast);
  padding: 20px;
}

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

.modal-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 850px;
  max-height: 90vh;
  overflow-y: auto;
  position: relative;
  box-shadow: 0 25px 60px rgba(0, 0, 0, 0.8);
  transform: scale(0.95);
  transition: transform var(--transition-fast);
}

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

.modal-close {
  position: absolute;
  top: 16px;
  right: 16px;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid var(--border-light);
  color: var(--text-main);
  width: 36px;
  height: 36px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: background var(--transition-fast);
  z-index: 10;
}

.modal-close:hover {
  background: rgba(255, 255, 255, 0.2);
  color: var(--accent-cyan);
}

.modal-body {
  padding: 36px;
}

/* 5-Page Interactive PDF Lightbox Reader */
.lightbox-card {
  max-width: 900px;
  background: #0B1120;
}

.reader-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--bg-card);
  padding: 12px 20px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-light);
  margin-bottom: 20px;
}

.page-nav-controls {
  display: flex;
  align-items: center;
  gap: 12px;
}

.page-indicator {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--accent-cyan);
  font-weight: 700;
  background: rgba(14, 165, 233, 0.1);
  padding: 4px 12px;
  border-radius: var(--radius-pill);
}

.pdf-viewer-frame {
  background: #FFFFFF;
  border-radius: var(--radius-md);
  padding: 36px;
  color: #0F172A;
  box-shadow: 0 10px 40px rgba(0, 0, 0, 0.5);
  min-height: 480px;
  position: relative;
}

.pdf-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 2px solid #0F172A;
  padding-bottom: 12px;
  margin-bottom: 24px;
}

.pdf-doc-title {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 0.85rem;
  letter-spacing: 0.5px;
  color: #0F172A;
}

.pdf-badge {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: #0EA5E9;
  font-weight: 700;
  background: #E0F2FE;
  padding: 4px 10px;
  border-radius: 4px;
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 3000;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.toast {
  background: var(--bg-card);
  border: 1px solid var(--accent-cyan);
  color: var(--text-main);
  padding: 14px 20px;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-glow);
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.9rem;
  animation: slideIn 0.3s ease forwards;
}

@keyframes slideIn {
  from { transform: translateX(100%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}

/* Responsive Media Queries */
@media (max-width: 1200px) {
  .books-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 900px) {
  .books-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .hero-grid, .product-layout, .about-grid, .contact-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  .sample-thumbnails {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 600px) {
  .books-grid {
    grid-template-columns: 1fr;
  }
  .sample-thumbnails {
    grid-template-columns: repeat(2, 1fr);
  }
  .hero-headline {
    font-size: 2.2rem;
  }
  .nav-menu {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 80px;
    left: 0;
    width: 100%;
    background: var(--bg-card);
    padding: 20px;
    border-bottom: 1px solid var(--border-light);
  }
  .nav-menu.active {
    display: flex;
  }
  .mobile-toggle {
    display: block;
  }
  .product-layout {
    padding: 24px;
  }
  .spec-grid {
    grid-template-columns: 1fr;
    padding: 14px;
  }
  .sample-title {
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
  }
  .buy-action-box {
    flex-direction: column;
    align-items: stretch;
    text-align: center;
    padding: 16px;
    gap: 16px;
  }
  .buy-action-box .checkout-price-display {
    display: flex;
    flex-direction: column;
    align-items: center;
  }
  .hero-ctas, .hero-stats {
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
  }
  .detail-modal-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }
  .modal-buy-box {
    flex-direction: column;
    align-items: stretch;
    gap: 16px;
    text-align: center;
  }
  .reader-toolbar {
    flex-direction: column;
    align-items: stretch;
    gap: 16px;
    padding: 16px;
  }
  .reader-toolbar-info {
    flex-direction: column;
    text-align: center;
  }
  .reader-toolbar-info i {
    display: none;
  }
  .page-nav-controls {
    justify-content: center;
    flex-wrap: wrap;
  }
}