/* ==========================================================================
   青云梯机场 (Qingyunti Cloud Airport) Design System
   Theme: 蜀道剑阁垂直天梯：冷灰崖壁青苔刻线与古法栈道
   Palette: Cold Granite Slate (#EEEEF2), Dark Basalt (#1A1D24), Celadon Lichen (#3B7A57), Bronze Anchor (#9E866C / #B89B74)
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+SC:wght@400;600;700;900&family=Inter:wght@300;400;500;600;700;800&family=Fira+Code:wght@400;500&display=swap');

:root {
  /* Color Palette */
  --color-bg-granite: #EEEEF2;
  --color-bg-rock-light: #E4E6EC;
  --color-bg-rock-mid: #D5D8E0;
  --color-basalt-dark: #1A1D24;
  --color-basalt-deeper: #121419;
  --color-basalt-card: #222630;
  
  --color-text-main: #1C2029;
  --color-text-muted: #5A6273;
  --color-text-light: #F2F4F8;
  --color-text-dim: #94A0B4;

  /* Accent Colors */
  --color-lichen: #3B7A57;
  --color-lichen-alpha: rgba(59, 122, 87, 0.2);
  --color-lichen-bright: #4DA674;
  --color-lichen-glow: rgba(77, 166, 116, 0.35);
  
  --color-bronze: #9E866C;
  --color-bronze-light: #B89B74;
  --color-bronze-dark: #6E5A47;
  --color-bronze-alpha: rgba(158, 134, 108, 0.25);

  --color-cinnabar-seal: #C83B2B;
  --color-gold-ink: #D4AF37;

  /* Fonts */
  --font-serif: 'Noto Serif SC', 'Songti SC', 'Source Han Serif SC', Georgia, serif;
  --font-sans: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-code: 'Fira Code', Consolas, monospace;

  /* Shadows & Borders */
  --border-chiseled: 1px solid rgba(26, 29, 36, 0.12);
  --border-basalt: 1px solid rgba(255, 255, 255, 0.08);
  --border-bronze: 1px solid rgba(184, 155, 116, 0.4);
  --shadow-rock: 0 10px 30px -5px rgba(18, 20, 25, 0.08), 0 4px 12px rgba(18, 20, 25, 0.04);
  --shadow-basalt-depth: inset 0 2px 6px rgba(0, 0, 0, 0.4), 0 20px 40px rgba(0,0,0,0.3);

  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-pill: 9999px;

  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

body {
  background-color: var(--color-bg-granite);
  color: var(--color-text-main);
  font-family: var(--font-sans);
  line-height: 1.7;
  overflow-x: hidden;
  position: relative;
  background-image: 
    radial-gradient(circle at 15% 20%, rgba(59, 122, 87, 0.04) 0%, transparent 40%),
    radial-gradient(circle at 85% 75%, rgba(158, 134, 108, 0.05) 0%, transparent 45%),
    linear-gradient(to bottom, #EEEEF2 0%, #E8EAEF 50%, #EEEEF2 100%);
}

/* Background Texture Overlay */
body::before {
  content: "";
  position: fixed;
  top: 0; left: 0; right: 0; bottom: 0;
  background-image: url("data:image/svg+xml,%3Csvg width='100' height='100' viewBox='0 0 100 100' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M11 18l2-2m20 40l-3 3m40-10l2 2m-60 20l4-4m70-30l-2 2' stroke='%201C2029' stroke-width='0.4' stroke-opacity='0.03' fill='none'/%3E%3C/svg%3E");
  pointer-events: none;
  z-index: 0;
}

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

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

.container {
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 24px;
  position: relative;
  z-index: 2;
}

/* REMOVED: .vertical-anchor-spine (Middle line removed as requested) */

/* Header & Navigation */
.header-navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(238, 238, 242, 0.94);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: var(--border-chiseled);
  transition: all 0.3s ease;
}

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

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-family: var(--font-serif);
  font-weight: 900;
  font-size: 1.4rem;
  letter-spacing: 1px;
  color: var(--color-basalt-dark);
}

.brand-logo-icon {
  width: 40px;
  height: 40px;
  background: var(--color-basalt-dark);
  border: 1.5px solid var(--color-bronze-light);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  box-shadow: 0 4px 10px rgba(0,0,0,0.15);
}

.brand-logo-icon::after {
  content: "青";
  font-family: var(--font-serif);
  font-size: 20px;
  color: #EEEEF2;
  font-weight: 700;
}

.brand-logo-icon .lichen-dot {
  position: absolute;
  top: 4px;
  right: 4px;
  width: 6px;
  height: 6px;
  background-color: var(--color-lichen-bright);
  border-radius: 50%;
  box-shadow: 0 0 8px var(--color-lichen-bright);
}

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

.nav-links a {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text-muted);
  transition: var(--transition-fast);
  position: relative;
  padding: 6px 0;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-basalt-dark);
}

.nav-links a::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0%;
  height: 2px;
  background-color: var(--color-lichen);
  transition: var(--transition-fast);
}

.nav-links a:hover::after {
  width: 100%;
}

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

/* Custom Buttons */
.btn-plankway {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 28px;
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 1rem;
  color: #EEEEF2;
  background: var(--color-basalt-dark);
  border: 1px solid var(--color-bronze-light);
  border-radius: var(--radius-sm);
  cursor: pointer;
  position: relative;
  overflow: hidden;
  box-shadow: 0 6px 18px rgba(26, 29, 36, 0.25);
  transition: var(--transition-normal);
}

.btn-plankway::before {
  content: "";
  position: absolute;
  top: 0; left: -100%;
  width: 100%; height: 100%;
  background: linear-gradient(90deg, transparent, rgba(77, 166, 116, 0.25), transparent);
  transition: 0.5s;
}

.btn-plankway:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 25px rgba(26, 29, 36, 0.35);
  border-color: var(--color-lichen-bright);
  color: #FFFFFF;
}

.btn-plankway:hover::before {
  left: 100%;
}

.btn-plankway-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--color-basalt-dark);
  background: rgba(255, 255, 255, 0.6);
  border: 1px solid rgba(26, 29, 36, 0.18);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition-fast);
}

.btn-plankway-secondary:hover {
  background: #FFFFFF;
  border-color: var(--color-basalt-dark);
  transform: translateY(-2px);
}

/* Mobile Menu Toggle */
.mobile-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 24px;
  cursor: pointer;
  color: var(--color-basalt-dark);
  padding: 4px;
}

/* Section Common Styling */
.section-padding {
  padding: 90px 0;
  position: relative;
}

.section-header {
  text-align: center;
  max-width: 780px;
  margin: 0 auto 60px;
}

.section-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 4px 14px;
  background: var(--color-lichen-alpha);
  border: 1px solid var(--color-lichen);
  border-radius: var(--radius-pill);
  font-size: 0.825rem;
  font-weight: 700;
  letter-spacing: 1.5px;
  color: var(--color-lichen);
  text-transform: uppercase;
  margin-bottom: 16px;
}

.section-title {
  font-family: var(--font-serif);
  font-size: 2.3rem;
  font-weight: 900;
  color: var(--color-basalt-dark);
  line-height: 1.35;
  margin-bottom: 16px;
  letter-spacing: -0.5px;
}

.section-subtitle {
  font-size: 1.05rem;
  color: var(--color-text-muted);
  line-height: 1.8;
}

/* Ancient Carved Stone Slab (摩崖阴刻拓片 Style) */
.carved-stone-slab {
  background: var(--color-basalt-dark);
  color: var(--color-text-light);
  border-radius: var(--radius-md);
  border: 1px solid rgba(255, 255, 255, 0.1);
  padding: 40px;
  position: relative;
  box-shadow: var(--shadow-basalt-depth);
  overflow: hidden;
}

.carved-stone-slab::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0; bottom: 0;
  background-image: radial-gradient(circle at 50% 0%, rgba(184, 155, 116, 0.12), transparent 70%);
  pointer-events: none;
}

/* Rubbings Stamp (阴刻拓印印章) */
.rubbing-seal {
  width: 52px;
  height: 52px;
  border: 2px solid var(--color-cinnabar-seal);
  color: var(--color-cinnabar-seal);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-serif);
  font-size: 18px;
  font-weight: 900;
  line-height: 1.1;
  padding: 4px;
  text-align: center;
  transform: rotate(-6deg);
  user-select: none;
  box-shadow: 0 0 10px rgba(200, 59, 43, 0.15);
}

/* HERO SECTION */
.hero-section {
  padding: 80px 0 100px;
  position: relative;
  overflow: hidden;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 50px;
  align-items: center;
}

.hero-badge-wrap {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 6px 16px;
  background: rgba(26, 29, 36, 0.06);
  border: 1px solid rgba(158, 134, 108, 0.3);
  border-radius: var(--radius-pill);
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-basalt-dark);
  margin-bottom: 24px;
}

.hero-badge-icon {
  width: 8px;
  height: 8px;
  background-color: var(--color-lichen-bright);
  border-radius: 50%;
  animation: pulse-lichen 2s infinite;
}

@keyframes pulse-lichen {
  0% { box-shadow: 0 0 0 0 rgba(77, 166, 116, 0.6); }
  70% { box-shadow: 0 0 0 10px rgba(77, 166, 116, 0); }
  100% { box-shadow: 0 0 0 0 rgba(77, 166, 116, 0); }
}

.hero-h1 {
  font-family: var(--font-serif);
  font-size: 3.2rem;
  font-weight: 900;
  color: var(--color-basalt-dark);
  line-height: 1.2;
  letter-spacing: -1px;
  margin-bottom: 24px;
}

.hero-h1 span.highlight {
  position: relative;
  display: inline-block;
  color: var(--color-basalt-dark);
  background: linear-gradient(120deg, rgba(59, 122, 87, 0.15) 0%, rgba(184, 155, 116, 0.2) 100%);
  padding: 0 8px;
  border-radius: 4px;
}

.hero-desc {
  font-size: 1.125rem;
  color: var(--color-text-muted);
  line-height: 1.85;
  margin-bottom: 36px;
}

.hero-cta-box {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px;
  margin-bottom: 40px;
}

.hero-feature-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  padding-top: 24px;
  border-top: 1px dashed rgba(26, 29, 36, 0.15);
}

.hero-feature-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-text-main);
}

.hero-feature-item svg {
  color: var(--color-lichen);
}

/* Speed Carved Stone Tablet (Hero Visual Right) */
.hero-stone-card {
  position: relative;
}

.stone-carving-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  padding-bottom: 20px;
  margin-bottom: 24px;
}

.stone-title-text {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: 1px;
  color: #EEEEF2;
}

.stone-title-sub {
  font-size: 0.8rem;
  color: var(--color-text-dim);
  font-family: var(--font-code);
}

.stone-metric-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin-bottom: 24px;
}

.stone-metric-box {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-sm);
  padding: 16px;
}

.stone-metric-val {
  font-family: var(--font-code);
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--color-lichen-bright);
}

.stone-metric-lbl {
  font-size: 0.8rem;
  color: var(--color-text-dim);
  margin-top: 4px;
}

.stone-node-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.stone-node-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 14px;
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
}

.node-flag-title {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
}

.node-ping {
  font-family: var(--font-code);
  color: var(--color-lichen-bright);
  font-weight: 600;
}

/* CORE ADVANTAGES ( Cliffside Plankway Architecture ) */
.advantages-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
}

.plankway-node-card {
  background: rgba(255, 255, 255, 0.7);
  backdrop-filter: blur(8px);
  border: 1px solid rgba(26, 29, 36, 0.12);
  border-radius: var(--radius-md);
  padding: 36px 28px;
  position: relative;
  transition: var(--transition-normal);
  display: flex;
  flex-direction: column;
}

.plankway-node-card::before {
  content: "";
  position: absolute;
  top: 0; left: 0;
  width: 4px;
  height: 0%;
  background: var(--color-lichen-bright);
  transition: var(--transition-normal);
  border-top-left-radius: var(--radius-md);
}

.plankway-node-card:hover {
  transform: translateY(-6px);
  background: #FFFFFF;
  border-color: rgba(59, 122, 87, 0.4);
  box-shadow: var(--shadow-rock);
}

.plankway-node-card:hover::before {
  height: 100%;
}

.plankway-icon-wrap {
  width: 54px;
  height: 54px;
  background: var(--color-basalt-dark);
  color: var(--color-bronze-light);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 20px;
  margin-bottom: 24px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.12);
}

.plankway-card-title {
  font-family: var(--font-serif);
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--color-basalt-dark);
  margin-bottom: 12px;
}

.plankway-card-desc {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  line-height: 1.7;
}

/* PRICING PACKAGES ( Cliff Planks Pricing ) */
.pricing-switcher {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  margin-bottom: 48px;
}

.switcher-btn {
  padding: 10px 24px;
  font-size: 0.95rem;
  font-weight: 700;
  border: 1px solid rgba(26, 29, 36, 0.15);
  background: rgba(255, 255, 255, 0.5);
  border-radius: var(--radius-pill);
  cursor: pointer;
  transition: var(--transition-fast);
}

.switcher-btn.active {
  background: var(--color-basalt-dark);
  color: #EEEEF2;
  border-color: var(--color-bronze-light);
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
  align-items: stretch;
}

.pricing-card {
  background: #FFFFFF;
  border: 1px solid rgba(26, 29, 36, 0.12);
  border-radius: var(--radius-lg);
  padding: 40px 32px;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: var(--transition-normal);
  box-shadow: var(--shadow-rock);
}

.pricing-card.featured {
  background: var(--color-basalt-dark);
  color: var(--color-text-light);
  border: 1.5px solid var(--color-bronze-light);
  transform: scale(1.03);
}

.featured-badge {
  position: absolute;
  top: -14px;
  right: 24px;
  background: var(--color-bronze-light);
  color: var(--color-basalt-dark);
  font-size: 0.75rem;
  font-weight: 800;
  padding: 4px 14px;
  border-radius: var(--radius-pill);
  letter-spacing: 1px;
}

.pricing-plan-name {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  font-weight: 800;
  margin-bottom: 8px;
}

.pricing-plan-desc {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: 24px;
}

.pricing-card.featured .pricing-plan-desc {
  color: var(--color-text-dim);
}

.pricing-price-wrap {
  display: flex;
  align-items: baseline;
  gap: 4px;
  margin-bottom: 28px;
}

.price-symbol {
  font-size: 1.4rem;
  font-weight: 700;
}

.price-amount {
  font-family: var(--font-serif);
  font-size: 3rem;
  font-weight: 900;
  line-height: 1;
}

.price-period {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}

.pricing-card.featured .price-period {
  color: var(--color-text-dim);
}

.pricing-features-list {
  list-style: none;
  margin-bottom: 36px;
  flex-grow: 1;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.pricing-features-list li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.925rem;
}

.pricing-features-list li svg {
  color: var(--color-lichen);
  flex-shrink: 0;
}

.pricing-card.featured .pricing-features-list li svg {
  color: var(--color-lichen-bright);
}

/* AUDIENCE SUITABILITY (适合人群) */
.audience-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.audience-card {
  background: rgba(255, 255, 255, 0.6);
  border: 1px solid rgba(26, 29, 36, 0.1);
  border-radius: var(--radius-md);
  padding: 28px 22px;
  text-align: center;
  transition: var(--transition-fast);
}

.audience-card:hover {
  background: #FFFFFF;
  transform: translateY(-4px);
  box-shadow: var(--shadow-rock);
  border-color: var(--color-bronze);
}

.audience-icon {
  width: 56px;
  height: 56px;
  margin: 0 auto 18px;
  background: var(--color-bg-rock-light);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-basalt-dark);
}

.audience-title {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.audience-desc {
  font-size: 0.875rem;
  color: var(--color-text-muted);
  line-height: 1.65;
}

/* TUTORIAL SECTION ( Clash & Clash Party 教程 ) */
.tutorial-tab-nav {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-bottom: 40px;
  flex-wrap: wrap;
}

.tab-btn {
  padding: 12px 28px;
  font-size: 0.95rem;
  font-weight: 700;
  background: rgba(255, 255, 255, 0.5);
  border: 1px solid rgba(26, 29, 36, 0.15);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition-fast);
  display: flex;
  align-items: center;
  gap: 8px;
}

.tab-btn.active {
  background: var(--color-basalt-dark);
  color: #EEEEF2;
  border-color: var(--color-bronze-light);
}

.tutorial-content-panel {
  display: none;
}

.tutorial-content-panel.active {
  display: block;
}

.tutorial-steps-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.step-card {
  background: #FFFFFF;
  border: 1px solid rgba(26, 29, 36, 0.12);
  border-radius: var(--radius-md);
  padding: 30px 24px;
  position: relative;
  display: flex;
  flex-direction: column;
}

.step-number {
  font-family: var(--font-code);
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--color-bronze-light);
  line-height: 1;
  margin-bottom: 16px;
}

.step-title {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 10px;
}

.step-desc {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.65;
}

/* REVIEWS / TESTIMONIALS ( 用户真实反馈 ) */
.reviews-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
}

.review-card {
  background: rgba(255, 255, 255, 0.7);
  border: 1px solid rgba(26, 29, 36, 0.1);
  border-radius: var(--radius-md);
  padding: 32px 26px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.review-quote {
  font-size: 0.95rem;
  color: var(--color-text-main);
  line-height: 1.75;
  margin-bottom: 24px;
  font-style: italic;
}

.review-author {
  display: flex;
  align-items: center;
  gap: 14px;
  border-top: 1px solid rgba(26, 29, 36, 0.08);
  padding-top: 16px;
}

.author-avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--color-basalt-dark);
  color: var(--color-bronze-light);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-family: var(--font-serif);
}

.author-name {
  font-weight: 700;
  font-size: 0.95rem;
}

.author-role {
  font-size: 0.8rem;
  color: var(--color-text-muted);
}

/* FAQ ACCORDION ( 常见问题 ) */
.faq-list {
  max-width: 880px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.faq-item {
  background: #FFFFFF;
  border: 1px solid rgba(26, 29, 36, 0.12);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: var(--transition-fast);
}

.faq-question {
  width: 100%;
  padding: 22px 28px;
  background: none;
  border: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-basalt-dark);
  text-align: left;
  cursor: pointer;
}

.faq-icon {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--color-bg-granite);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  transition: transform 0.3s ease;
  flex-shrink: 0;
  font-family: var(--font-sans);
}

.faq-item.active .faq-icon {
  transform: rotate(45deg);
  background: var(--color-basalt-dark);
  color: #EEEEF2;
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease, padding 0.35s ease;
  padding: 0 28px;
  color: var(--color-text-muted);
  font-size: 0.95rem;
  line-height: 1.8;
}

.faq-item.active .faq-answer {
  max-height: 400px;
  padding: 0 28px 24px 28px;
}

/* ARTICLE HUB MATRIX ( 文章目录 ) */
.articles-matrix-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 30px;
}

.article-card-item {
  background: rgba(255, 255, 255, 0.85);
  border: 1px solid rgba(26, 29, 36, 0.12);
  border-radius: var(--radius-md);
  padding: 32px 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: var(--transition-normal);
}

.article-card-item:hover {
  background: #FFFFFF;
  transform: translateY(-4px);
  border-color: var(--color-lichen);
  box-shadow: var(--shadow-rock);
}

.article-meta-tag {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--color-lichen);
  margin-bottom: 12px;
}

.article-card-title {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--color-basalt-dark);
  line-height: 1.4;
  margin-bottom: 12px;
}

.article-card-excerpt {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.7;
  margin-bottom: 20px;
}

.article-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.85rem;
  color: var(--color-text-dim);
  border-top: 1px solid rgba(26, 29, 36, 0.08);
  padding-top: 16px;
}

.read-more-link {
  font-weight: 700;
  color: var(--color-basalt-dark);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.read-more-link:hover {
  color: var(--color-lichen);
}

/* FOOTER ( 页脚网站地图与声明 ) */
.footer-site {
  background: var(--color-basalt-dark);
  color: var(--color-text-light);
  padding: 80px 0 40px;
  border-top: 2px solid var(--color-bronze-light);
  position: relative;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr repeat(3, 1fr);
  gap: 50px;
  margin-bottom: 60px;
}

.footer-brand-desc {
  font-size: 0.9rem;
  color: var(--color-text-dim);
  line-height: 1.8;
  margin-top: 16px;
}

.footer-col-title {
  font-family: var(--font-serif);
  font-size: 1.1rem;
  font-weight: 700;
  color: #EEEEF2;
  margin-bottom: 20px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  padding-bottom: 10px;
}

.footer-links-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.footer-links-list a {
  font-size: 0.9rem;
  color: var(--color-text-dim);
  transition: var(--transition-fast);
}

.footer-links-list a:hover {
  color: var(--color-lichen-bright);
}

.footer-bottom-bar {
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  padding-top: 30px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 20px;
  font-size: 0.85rem;
  color: var(--color-text-dim);
}

.footer-legal-links {
  display: flex;
  gap: 20px;
}

.footer-legal-links a:hover {
  color: #FFFFFF;
}

/* ARTICLE DETAIL PAGES SPECIFIC CSS */
.article-header {
  padding: 60px 0 40px;
  background: rgba(26, 29, 36, 0.03);
  border-bottom: var(--border-chiseled);
  margin-bottom: 50px;
}

.breadcrumb-nav {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-bottom: 20px;
}

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

.article-h1 {
  font-family: var(--font-serif);
  font-size: 2.5rem;
  font-weight: 900;
  color: var(--color-basalt-dark);
  line-height: 1.3;
  margin-bottom: 20px;
}

.article-meta-info {
  display: flex;
  flex-wrap: wrap;
  gap: 24px;
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.article-body-layout {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 50px;
}

.article-content-main {
  font-size: 1.05rem;
  line-height: 1.9;
  color: #2D333F;
}

.article-content-main h2 {
  font-family: var(--font-serif);
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--color-basalt-dark);
  margin: 44px 0 20px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--color-bg-rock-mid);
}

.article-content-main h3 {
  font-family: var(--font-serif);
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--color-basalt-dark);
  margin: 32px 0 16px;
}

.article-content-main p {
  margin-bottom: 24px;
}

.article-content-main ul, 
.article-content-main ol {
  margin-bottom: 24px;
  padding-left: 24px;
}

.article-content-main li {
  margin-bottom: 8px;
}

.article-content-main blockquote {
  background: rgba(59, 122, 87, 0.08);
  border-left: 4px solid var(--color-lichen);
  padding: 20px 24px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin-bottom: 28px;
  font-style: italic;
  font-weight: 500;
}

.article-sidebar {
  position: sticky;
  top: 100px;
  height: fit-content;
}

.sidebar-widget {
  background: #FFFFFF;
  border: 1px solid rgba(26, 29, 36, 0.12);
  border-radius: var(--radius-md);
  padding: 28px 24px;
  margin-bottom: 30px;
  box-shadow: var(--shadow-rock);
}

.sidebar-widget-title {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--color-basalt-dark);
  margin-bottom: 18px;
  padding-bottom: 10px;
  border-bottom: 1px solid rgba(26, 29, 36, 0.1);
}

.recommended-articles-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.recommended-articles-list a {
  font-size: 0.925rem;
  font-weight: 600;
  color: var(--color-text-main);
  line-height: 1.5;
  transition: var(--transition-fast);
  display: block;
}

.recommended-articles-list a:hover {
  color: var(--color-lichen);
}

/* RESPONSIVE MEDIA QUERIES */
@media (max-width: 1024px) {
  .hero-grid,
  .article-body-layout {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .advantages-grid,
  .pricing-grid,
  .reviews-grid,
  .tutorial-steps-grid {
    grid-template-columns: repeat(2, 1fr);
  }

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

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

  .pricing-card.featured {
    transform: none;
  }

  .hero-h1 {
    font-size: 2.6rem;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .mobile-toggle {
    display: block;
  }

  .nav-links.mobile-open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 80px;
    left: 0;
    right: 0;
    background: var(--color-bg-granite);
    padding: 24px;
    border-bottom: var(--border-chiseled);
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
  }

  .advantages-grid,
  .pricing-grid,
  .reviews-grid,
  .articles-matrix-grid,
  .tutorial-steps-grid,
  .audience-grid {
    grid-template-columns: 1fr;
  }

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

  .hero-h1 {
    font-size: 2.1rem;
  }

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