/* ========================================
   Thirty-Six Stratagems | 兵法三十六计
   Global Styles - Responsive & SEO Optimized
   ======================================== */

:root {
  --gold: #C9A84C;
  --gold-light: #D4BC6A;
  --gold-dark: #A88A32;
  --ink: #1A1A1A;
  --ink-light: #2D2D2D;
  --ivory: #F8F5F0;
  --ivory-dark: #EDE8E0;
  --text-primary: #1A1A1A;
  --text-secondary: #555555;
  --text-light: #888888;
  --border: #E0DBD4;
  --shadow: rgba(26, 26, 26, 0.08);
  --shadow-lg: rgba(26, 26, 26, 0.15);
  --radius: 8px;
  --radius-lg: 12px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --max-width: 1200px;
  --nav-height: 72px;
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-height) + 20px);
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--ivory);
  color: var(--text-primary);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.cn-text {
  font-family: 'Noto Sans SC', 'Source Han Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  font-size: 0.7em;
  color: var(--text-light);
  font-weight: 400;
}

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

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

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* ========== NAVIGATION ========== */
.nav {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(26, 26, 26, 0.97);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(201, 168, 76, 0.2);
  height: var(--nav-height);
}

.nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}

.nav-brand {
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
}

.nav-brand-en {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--gold);
  letter-spacing: 0.5px;
  line-height: 1.3;
}

.nav-brand-cn {
  font-family: 'Noto Sans SC', sans-serif;
  font-size: 0.65rem;
  color: rgba(255, 255, 255, 0.45);
  letter-spacing: 2px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
}

.nav-links a {
  color: rgba(255, 255, 255, 0.75);
  font-size: 0.85rem;
  font-weight: 500;
  padding: 8px 14px;
  border-radius: 6px;
  transition: var(--transition);
  white-space: nowrap;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--gold);
  background: rgba(201, 168, 76, 0.1);
}

.nav-links .cn-text {
  display: inline;
  margin-left: 4px;
  font-size: 0.6rem;
}

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

.lang-toggle {
  display: flex;
  align-items: center;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 20px;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.lang-btn {
  padding: 6px 14px;
  font-size: 0.75rem;
  font-weight: 600;
  color: rgba(255, 255, 255, 0.5);
  background: transparent;
  border: none;
  cursor: pointer;
  transition: var(--transition);
}

.lang-btn.active {
  background: var(--gold);
  color: var(--ink);
}

.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.hamburger span {
  width: 22px;
  height: 2px;
  background: var(--gold);
  transition: var(--transition);
  border-radius: 2px;
}

/* Mobile Nav */
.nav-mobile {
  display: none;
  position: fixed;
  top: var(--nav-height);
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(26, 26, 26, 0.98);
  z-index: 999;
  padding: 24px;
  overflow-y: auto;
}

.nav-mobile.open {
  display: block;
}

.nav-mobile a {
  display: block;
  color: rgba(255, 255, 255, 0.8);
  font-size: 1rem;
  font-weight: 500;
  padding: 14px 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  transition: var(--transition);
}

.nav-mobile a:hover {
  color: var(--gold);
  padding-left: 8px;
}

/* ========== HERO SECTION ========== */
.hero {
  background: var(--ink);
  color: #fff;
  padding: 100px 0 80px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(201, 168, 76, 0.08) 0%, transparent 70%);
  border-radius: 50%;
}

.hero .container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
}

.hero-title {
  font-size: 3.2rem;
  font-weight: 800;
  line-height: 1.15;
  color: var(--gold);
  margin-bottom: 8px;
  letter-spacing: -0.5px;
}

.hero-title-cn {
  font-family: 'Noto Sans SC', sans-serif;
  font-size: 1rem;
  color: rgba(255, 255, 255, 0.35);
  margin-bottom: 24px;
  font-weight: 400;
  letter-spacing: 4px;
}

.hero-subtitle {
  font-size: 1.1rem;
  color: rgba(255, 255, 255, 0.7);
  line-height: 1.8;
  margin-bottom: 12px;
  max-width: 520px;
}

.hero-subtitle-cn {
  font-family: 'Noto Sans SC', sans-serif;
  font-size: 0.82rem;
  color: rgba(255, 255, 255, 0.35);
  margin-bottom: 36px;
  max-width: 480px;
}

.hero-cta {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 28px;
  font-size: 0.92rem;
  font-weight: 600;
  border-radius: 8px;
  border: none;
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
}

.btn-primary {
  background: var(--gold);
  color: var(--ink);
}

.btn-primary:hover {
  background: var(--gold-light);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(201, 168, 76, 0.3);
}

.btn-outline {
  background: transparent;
  color: var(--gold);
  border: 1.5px solid var(--gold);
}

.btn-outline:hover {
  background: rgba(201, 168, 76, 0.1);
  transform: translateY(-2px);
}

.hero-visual {
  display: flex;
  justify-content: center;
  align-items: center;
}

.hero-emblem {
  width: 100%;
  max-width: 520px;
}

/* ========== SECTION COMMON ========== */
.section {
  padding: 80px 0;
}

.section-dark {
  background: var(--ink);
  color: #fff;
}

.section-header {
  text-align: center;
  margin-bottom: 56px;
}

.section-title {
  font-size: 2rem;
  font-weight: 700;
  color: inherit;
  margin-bottom: 4px;
}

.section-title-cn {
  font-family: 'Noto Sans SC', sans-serif;
  font-size: 0.85rem;
  color: var(--text-light);
  margin-bottom: 16px;
}

.section-dark .section-title-cn {
  color: rgba(255, 255, 255, 0.35);
}

.section-desc {
  font-size: 1rem;
  color: var(--text-secondary);
  max-width: 640px;
  margin: 0 auto;
  line-height: 1.8;
}

.section-dark .section-desc {
  color: rgba(255, 255, 255, 0.6);
}

/* ========== INTRO CARDS ========== */
.intro-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.intro-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 36px 28px;
  text-align: center;
  transition: var(--transition);
}

.intro-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 32px var(--shadow-lg);
  border-color: var(--gold);
}

.intro-icon {
  font-size: 2.4rem;
  margin-bottom: 16px;
}

.intro-card h3 {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.intro-card .cn-text {
  display: block;
  margin-bottom: 12px;
}

.intro-card p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ========== CATEGORY CARDS ========== */
.category-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.category-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 32px 24px;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.category-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gold);
  transform: scaleX(0);
  transition: var(--transition);
}

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

.category-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 32px var(--shadow-lg);
}

.category-number {
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--gold);
  text-transform: uppercase;
  letter-spacing: 2px;
  margin-bottom: 12px;
}

.category-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.category-card .cn-text {
  display: block;
  margin-bottom: 16px;
}

.category-points {
  list-style: none;
  margin-bottom: 20px;
}

.category-points li {
  font-size: 0.85rem;
  color: var(--text-secondary);
  padding: 6px 0;
  padding-left: 20px;
  position: relative;
}

.category-points li::before {
  content: '◆';
  position: absolute;
  left: 0;
  color: var(--gold);
  font-size: 0.6rem;
  top: 9px;
}

.category-link {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--gold);
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: var(--transition);
}

.category-link:hover {
  gap: 10px;
}

/* ========== STRATAGEM CARDS ========== */
.stratagem-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.stratagem-grid-full {
  grid-template-columns: repeat(4, 1fr);
}

.stratagem-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 20px;
  transition: var(--transition);
  display: flex;
  flex-direction: column;
}

.stratagem-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 24px var(--shadow);
  border-color: var(--gold);
}

.stratagem-num {
  font-size: 0.7rem;
  font-weight: 700;
  color: var(--gold);
  letter-spacing: 1px;
  margin-bottom: 8px;
}

.stratagem-card h3 {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 2px;
  line-height: 1.4;
}

.stratagem-card .cn-text {
  display: block;
  margin-bottom: 10px;
}

.stratagem-card p {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.6;
  flex: 1;
  margin-bottom: 14px;
}

.stratagem-link {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--gold);
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin-top: auto;
  transition: var(--transition);
}

.stratagem-link:hover {
  gap: 8px;
}

/* ========== FEATURED STRATAGEMS ========== */
.featured-scroll {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.featured-card {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(201, 168, 76, 0.15);
  border-radius: var(--radius-lg);
  padding: 36px 28px;
  transition: var(--transition);
}

.featured-card:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: var(--gold);
  transform: translateY(-4px);
}

.featured-card h3 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--gold);
  margin-bottom: 4px;
}

.featured-card .cn-text {
  color: rgba(255, 255, 255, 0.4);
  margin-bottom: 14px;
}

.featured-card p {
  font-size: 0.88rem;
  color: rgba(255, 255, 255, 0.6);
  line-height: 1.7;
  margin-bottom: 18px;
}

.featured-card .btn-outline {
  font-size: 0.82rem;
  padding: 10px 20px;
}

/* ========== APPLICATION SCENARIOS ========== */
.scenario-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.scenario-item {
  text-align: center;
  padding: 32px 20px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  transition: var(--transition);
}

.scenario-item:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 24px var(--shadow);
  border-color: var(--gold);
}

.scenario-icon {
  font-size: 2.2rem;
  margin-bottom: 16px;
}

.scenario-item h3 {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.scenario-item .cn-text {
  display: block;
  margin-bottom: 10px;
}

.scenario-item p {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ========== FOOTER ========== */
.footer {
  background: var(--ink);
  color: rgba(255, 255, 255, 0.7);
  padding: 60px 0 30px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1.5fr;
  gap: 40px;
  margin-bottom: 40px;
}

.footer-brand {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--gold);
  margin-bottom: 12px;
}

.footer-desc {
  font-size: 0.85rem;
  line-height: 1.7;
  color: rgba(255, 255, 255, 0.5);
}

.footer h4 {
  font-size: 0.85rem;
  font-weight: 700;
  color: #fff;
  margin-bottom: 16px;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: 10px;
}

.footer-links a {
  font-size: 0.85rem;
  color: rgba(255, 255, 255, 0.5);
  transition: var(--transition);
}

.footer-links a:hover {
  color: var(--gold);
}

.newsletter-form {
  display: flex;
  gap: 8px;
  margin-top: 8px;
}

.newsletter-form input {
  flex: 1;
  padding: 10px 14px;
  border-radius: 6px;
  border: 1px solid rgba(255, 255, 255, 0.15);
  background: rgba(255, 255, 255, 0.05);
  color: #fff;
  font-size: 0.85rem;
  outline: none;
  transition: var(--transition);
}

.newsletter-form input:focus {
  border-color: var(--gold);
}

.newsletter-form button {
  padding: 10px 18px;
  background: var(--gold);
  color: var(--ink);
  border: none;
  border-radius: 6px;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  white-space: nowrap;
}

.newsletter-form button:hover {
  background: var(--gold-light);
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  padding-top: 24px;
  text-align: center;
  font-size: 0.78rem;
  color: rgba(255, 255, 255, 0.35);
}

/* ========== DETAIL PAGE ========== */
.detail-hero {
  background: var(--ink);
  color: #fff;
  padding: 60px 0 50px;
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.8rem;
  color: rgba(255, 255, 255, 0.4);
  margin-bottom: 28px;
  flex-wrap: wrap;
}

.breadcrumb a {
  color: rgba(255, 255, 255, 0.5);
  transition: var(--transition);
}

.breadcrumb a:hover {
  color: var(--gold);
}

.breadcrumb .sep {
  color: rgba(255, 255, 255, 0.2);
}

.detail-number {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--gold);
  letter-spacing: 2px;
  text-transform: uppercase;
  margin-bottom: 12px;
}

.detail-title {
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--gold);
  margin-bottom: 6px;
  line-height: 1.2;
}

.detail-title-cn {
  font-family: 'Noto Sans SC', sans-serif;
  font-size: 1.2rem;
  color: rgba(255, 255, 255, 0.4);
  margin-bottom: 20px;
  letter-spacing: 3px;
}

.detail-category-tag {
  display: inline-block;
  padding: 5px 14px;
  background: rgba(201, 168, 76, 0.15);
  color: var(--gold);
  font-size: 0.78rem;
  font-weight: 600;
  border-radius: 20px;
  border: 1px solid rgba(201, 168, 76, 0.3);
}

.detail-body {
  padding: 60px 0;
}

.detail-grid {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 48px;
}

.detail-section {
  margin-bottom: 40px;
}

.detail-section h2 {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 6px;
  color: var(--text-primary);
}

.detail-section .cn-text {
  display: block;
  margin-bottom: 16px;
}

.detail-section p {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.9;
  margin-bottom: 16px;
}

.detail-section .cn-paragraph {
  font-family: 'Noto Sans SC', sans-serif;
  font-size: 0.85rem;
  color: var(--text-light);
  line-height: 1.8;
  padding: 16px 20px;
  background: rgba(201, 168, 76, 0.04);
  border-left: 3px solid var(--gold);
  border-radius: 0 var(--radius) var(--radius) 0;
  margin-bottom: 16px;
}

.story-box {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 28px;
  margin-bottom: 16px;
}

.story-box h4 {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--gold);
  margin-bottom: 10px;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.story-box p {
  font-size: 0.9rem;
  line-height: 1.8;
}

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

.application-list li {
  padding: 14px 0;
  border-bottom: 1px solid var(--border);
  font-size: 0.9rem;
  color: var(--text-secondary);
  display: flex;
  align-items: flex-start;
  gap: 12px;
}

.application-list li:last-child {
  border-bottom: none;
}

.app-icon {
  flex-shrink: 0;
  font-size: 1.2rem;
  margin-top: 2px;
}

/* Sidebar */
.detail-sidebar {
  position: sticky;
  top: calc(var(--nav-height) + 24px);
  align-self: start;
}

.sidebar-card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  margin-bottom: 20px;
}

.sidebar-card h3 {
  font-size: 0.9rem;
  font-weight: 700;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.sidebar-nav {
  list-style: none;
}

.sidebar-nav li {
  margin-bottom: 6px;
}

.sidebar-nav a {
  display: block;
  font-size: 0.82rem;
  color: var(--text-secondary);
  padding: 8px 12px;
  border-radius: 6px;
  transition: var(--transition);
}

.sidebar-nav a:hover,
.sidebar-nav a.active {
  color: var(--gold);
  background: rgba(201, 168, 76, 0.06);
}

.sidebar-nav .cn-text {
  margin-left: 4px;
}

.adjacent-nav {
  display: flex;
  gap: 12px;
}

.adjacent-nav a {
  flex: 1;
  padding: 14px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-size: 0.82rem;
  transition: var(--transition);
  text-align: center;
}

.adjacent-nav a:hover {
  border-color: var(--gold);
  background: rgba(201, 168, 76, 0.04);
}

.adjacent-label {
  display: block;
  font-size: 0.7rem;
  color: var(--text-light);
  margin-bottom: 4px;
}

/* ========== CATEGORY PAGE ========== */
.category-hero {
  background: var(--ink);
  color: #fff;
  padding: 60px 0 50px;
}

.category-hero-title {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--gold);
  margin-bottom: 6px;
}

.category-hero-cn {
  font-family: 'Noto Sans SC', sans-serif;
  font-size: 1rem;
  color: rgba(255, 255, 255, 0.35);
  letter-spacing: 3px;
  margin-bottom: 16px;
}

.category-hero-desc {
  font-size: 1rem;
  color: rgba(255, 255, 255, 0.6);
  max-width: 640px;
  line-height: 1.8;
}

/* ========== ALL STRATAGEMS PAGE ========== */
.all-stratagems-group {
  margin-bottom: 48px;
}

.group-header {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 24px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--gold);
}

.group-header h2 {
  font-size: 1.3rem;
  font-weight: 700;
}

.group-header .cn-text {
  font-size: 0.85rem;
}

/* ========== RESPONSIVE ========== */
@media (max-width: 1024px) {
  .category-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .scenario-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .stratagem-grid-full {
    grid-template-columns: repeat(3, 1fr);
  }
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  :root {
    --nav-height: 60px;
  }

  .nav-links {
    display: none;
  }

  .hamburger {
    display: flex;
  }

  .hero .container {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .hero {
    padding: 60px 0 50px;
  }

  .hero-title {
    font-size: 2.2rem;
  }

  .hero-visual {
    order: -1;
  }

  .hero-emblem {
    max-width: 320px;
  }

  .hero-cta {
    flex-direction: column;
  }

  .btn {
    justify-content: center;
  }

  .intro-grid,
  .category-grid,
  .featured-scroll {
    grid-template-columns: 1fr;
  }

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

  .scenario-grid {
    grid-template-columns: 1fr;
  }

  .detail-grid {
    grid-template-columns: 1fr;
  }

  .detail-sidebar {
    position: static;
  }

  .detail-title {
    font-size: 1.8rem;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 30px;
  }

  .section {
    padding: 50px 0;
  }

  .section-title {
    font-size: 1.6rem;
  }

  .lang-toggle {
    display: none;
  }

  /* Mobile: show CN toggle */
  .cn-text-mobile-hidden {
    display: none;
  }
}

@media (max-width: 480px) {
  .stratagem-grid,
  .stratagem-grid-full {
    grid-template-columns: 1fr;
  }

  .hero-title {
    font-size: 1.8rem;
  }

  .container {
    padding: 0 16px;
  }
}

/* ========== STRUCTURED DATA (hidden) ========== */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}