/* ==========================================================================
   MESL 机场 ARCHITECTURAL FLOOR PLAN DESIGN SYSTEM
   Palette:
     White:           #FFFFFF
     Blueprint Navy:  #304966
     Warm Concrete:   #E9E6DF
     Muted Rust:      #A87560
   Typography:
     Headings:  Chinese Serif ("Noto Serif SC", "Songti SC", serif)
     Body:      System Sans-serif (17px)
     Diagrams:  Monospace ("SFMono-Regular", Consolas, monospace)
   Rules:
     - H1: 55px desktop / 35px mobile
     - Body: 17px
     - No neon colors
     - Thin dimension lines, drawing sheet cards, route line animations
     - Honor prefers-reduced-motion
   ========================================================================== */

:root {
  --color-white: #FFFFFF;
  --color-navy: #304966;
  --color-navy-dark: #1E3146;
  --color-navy-light: #415F82;
  --color-concrete: #E9E6DF;
  --color-concrete-light: #F7F6F2;
  --color-concrete-border: #D5D0C5;
  --color-rust: #A87560;
  --color-rust-light: #F6EDE8;
  --color-text-main: #1D2A38;
  --color-text-muted: #55687B;
  
  --font-serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", "SimSun", "STSong", serif;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, Courier, monospace;
  
  --container-max: 1240px;
  --grid-gap: 28px;
  --border-blueprint: 1px solid var(--color-navy);
  --border-dim: 1px solid var(--color-concrete-border);
}

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

html {
  font-size: 17px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.7;
  color: var(--color-text-main);
  background-color: var(--color-white);
  background-image: 
    linear-gradient(to right, rgba(233, 230, 223, 0.45) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(233, 230, 223, 0.45) 1px, transparent 1px);
  background-size: 32px 32px;
  min-height: 100vh;
  overflow-x: hidden;
  max-width: 100%;
}

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

a {
  color: var(--color-navy);
  text-decoration: none;
  transition: color 0.2s ease, border-color 0.2s ease, background-color 0.2s ease;
}

a:hover {
  color: var(--color-rust);
}

button {
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

/* Typography Scale */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-serif);
  color: var(--color-navy);
  line-height: 1.28;
  font-weight: 700;
  letter-spacing: -0.01em;
  overflow-wrap: anywhere;
}

h1 {
  font-size: 35px; /* Mobile first */
}

@media (min-width: 992px) {
  h1 {
    font-size: 55px; /* Desktop */
  }
}

h2 {
  font-size: 28px;
  margin-bottom: 16px;
  position: relative;
  display: inline-block;
}

@media (min-width: 768px) {
  h2 {
    font-size: 36px;
  }
}

h3 {
  font-size: 21px;
  margin-bottom: 12px;
}

@media (min-width: 768px) {
  h3 {
    font-size: 24px;
  }
}

h4 {
  font-size: 18px;
}

p {
  margin-bottom: 1rem;
  overflow-wrap: anywhere;
}

p:last-child {
  margin-bottom: 0;
}

.mono-label {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--color-rust);
}

/* Architectural Layout Elements */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin-left: auto;
  margin-right: auto;
  padding-left: 20px;
  padding-right: 20px;
}

@media (min-width: 768px) {
  .container {
    padding-left: 32px;
    padding-right: 32px;
  }
}

.section {
  padding-top: 64px;
  padding-bottom: 64px;
  position: relative;
}

@media (min-width: 992px) {
  .section {
    padding-top: 96px;
    padding-bottom: 96px;
  }
}

.section-alt {
  background-color: rgba(247, 246, 242, 0.7);
  border-top: 1px solid var(--color-concrete);
  border-bottom: 1px solid var(--color-concrete);
}

/* Dimension Line Elements */
.dimension-line {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 24px;
}

.dimension-line::before,
.dimension-line::after {
  content: "";
  flex: 1;
  height: 1px;
  background-color: var(--color-concrete-border);
  position: relative;
}

.dimension-line-navy::before,
.dimension-line-navy::after {
  background-color: var(--color-navy);
  opacity: 0.35;
}

.dimension-tag {
  font-family: var(--font-mono);
  font-size: 12px;
  padding: 3px 10px;
  background: var(--color-white);
  border: 1px solid var(--color-concrete-border);
  color: var(--color-navy);
  letter-spacing: 0.05em;
  white-space: nowrap;
}

/* Section Header */
.section-header {
  text-align: center;
  max-width: 760px;
  margin-left: auto;
  margin-right: auto;
  margin-bottom: 48px;
}

.section-header .sub-desc {
  color: var(--color-text-muted);
  font-size: 17px;
  margin-top: 12px;
}

/* Navigation Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-concrete);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 18px;
  color: var(--color-navy);
}

.brand-icon {
  width: 32px;
  height: 32px;
  background: var(--color-navy);
  border: 1px solid var(--color-navy);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-white);
  font-size: 14px;
}

.brand-tag {
  font-family: var(--font-mono);
  font-size: 11px;
  background: var(--color-concrete);
  padding: 2px 6px;
  border: 1px solid var(--color-concrete-border);
  color: var(--color-navy);
  font-weight: normal;
}

.nav-desktop {
  display: none;
}

@media (min-width: 992px) {
  .nav-desktop {
    display: flex;
    align-items: center;
    gap: 28px;
  }
  
  .nav-desktop a {
    font-size: 15px;
    font-weight: 500;
    color: var(--color-navy);
    padding: 6px 0;
    position: relative;
  }
  
  .nav-desktop a:hover,
  .nav-desktop a.active {
    color: var(--color-rust);
  }
  
  .nav-desktop a::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--color-rust);
    transition: width 0.2s ease;
  }
  
  .nav-desktop a:hover::after,
  .nav-desktop a.active::after {
    width: 100%;
  }
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 14px;
}

/* Button System */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 600;
  padding: 11px 22px;
  letter-spacing: 0.04em;
  border: 1px solid transparent;
  transition: all 0.2s ease;
  white-space: nowrap;
}

.btn-primary {
  background-color: var(--color-navy);
  color: var(--color-white);
  border-color: var(--color-navy);
}

.btn-primary:hover {
  background-color: var(--color-rust);
  border-color: var(--color-rust);
  color: var(--color-white);
}

.btn-secondary {
  background-color: var(--color-white);
  color: var(--color-navy);
  border-color: var(--color-navy);
}

.btn-secondary:hover {
  background-color: var(--color-concrete);
  color: var(--color-navy);
}

.btn-rust {
  background-color: var(--color-rust);
  color: var(--color-white);
  border-color: var(--color-rust);
}

.btn-rust:hover {
  background-color: var(--color-navy);
  border-color: var(--color-navy);
  color: var(--color-white);
}

.btn-sm {
  padding: 7px 14px;
  font-size: 12px;
}

.btn-block {
  width: 100%;
}

/* Mobile Menu Toggle */
.mobile-menu-btn {
  display: flex;
  flex-direction: column;
  justify-content: space-around;
  width: 32px;
  height: 32px;
  padding: 4px;
  background: var(--color-white);
  border: 1px solid var(--color-navy);
}

@media (min-width: 992px) {
  .mobile-menu-btn {
    display: none;
  }
}

.mobile-menu-btn span {
  width: 100%;
  height: 2px;
  background-color: var(--color-navy);
  transition: all 0.25s ease;
}

.mobile-menu-btn.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-btn.active span:nth-child(2) {
  opacity: 0;
}

.mobile-menu-btn.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* Mobile Drawer */
.mobile-drawer {
  display: none;
  position: fixed;
  top: 72px;
  left: 0;
  width: 100%;
  height: calc(100vh - 72px);
  background-color: var(--color-white);
  border-top: 1px solid var(--color-concrete);
  padding: 24px;
  overflow-y: auto;
  z-index: 999;
}

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

.mobile-nav-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-bottom: 28px;
}

.mobile-nav-links a {
  font-size: 18px;
  font-weight: 600;
  color: var(--color-navy);
  display: block;
  padding: 10px 0;
  border-bottom: 1px dashed var(--color-concrete);
}

/* Hero Section */
.hero-section {
  padding-top: 48px;
  padding-bottom: 64px;
  position: relative;
  overflow: hidden;
}

@media (min-width: 992px) {
  .hero-section {
    padding-top: 80px;
    padding-bottom: 100px;
  }
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 48px;
  align-items: center;
}

@media (min-width: 992px) {
  .hero-grid {
    grid-template-columns: 1.05fr 0.95fr;
    gap: 56px;
  }
}

.hero-copy {
  max-width: 620px;
}

.hero-title-block {
  border: 1px solid var(--color-concrete-border);
  background: var(--color-white);
  padding: 8px 14px;
  display: inline-flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 24px;
}

.hero-h1 {
  margin-bottom: 20px;
  letter-spacing: -0.02em;
}

.hero-lead {
  font-size: 18px;
  line-height: 1.75;
  color: var(--color-text-muted);
  margin-bottom: 32px;
}

.hero-cta-group {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 36px;
}

.hero-spec-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  padding-top: 24px;
  border-top: 1px dashed var(--color-concrete-border);
}

@media (min-width: 480px) {
  .hero-spec-list {
    grid-template-columns: repeat(4, 1fr);
  }
}

.hero-spec-item {
  border-left: 2px solid var(--color-rust);
  padding-left: 10px;
}

.hero-spec-val {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 15px;
  color: var(--color-navy);
}

.hero-spec-lbl {
  font-size: 12px;
  color: var(--color-text-muted);
}

/* Architectural Dashboard / Blueprint Canvas */
.blueprint-sheet {
  background: var(--color-white);
  border: 1px solid var(--color-navy);
  padding: 16px;
  position: relative;
  box-shadow: 6px 6px 0px rgba(48, 73, 102, 0.08);
}

@media (min-width: 768px) {
  .blueprint-sheet {
    padding: 24px;
  }
}

.sheet-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--color-navy);
  padding-bottom: 12px;
  margin-bottom: 16px;
}

.sheet-title {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: bold;
  color: var(--color-navy);
  letter-spacing: 0.06em;
}

.sheet-code {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-rust);
  border: 1px solid var(--color-rust);
  padding: 2px 6px;
}

/* Floor Plan Network SVG Animations */
.dashboard-svg {
  width: 100%;
  height: auto;
  border: 1px dashed var(--color-concrete-border);
  background-color: #FCFCF9;
}

/* Route Line Draw Once Animation */
.route-line {
  stroke-dasharray: 600;
  stroke-dashoffset: 600;
  animation: drawRouteLine 2.2s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

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

@media (prefers-reduced-motion: reduce) {
  .route-line {
    animation: none;
    stroke-dashoffset: 0;
  }
}

/* Sheet Title Block (Stamp) */
.dwg-title-block {
  margin-top: 16px;
  border: 1px solid var(--color-navy);
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  font-family: var(--font-mono);
  font-size: 11px;
  background: var(--color-white);
}

.dwg-cell {
  padding: 6px 10px;
  border-right: 1px solid var(--color-navy);
}

.dwg-cell:last-child {
  border-right: none;
}

.dwg-cell-lbl {
  color: var(--color-text-muted);
  font-size: 9px;
  text-transform: uppercase;
  display: block;
}

.dwg-cell-val {
  color: var(--color-navy);
  font-weight: bold;
}

/* Feature Advantages Section */
.features-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--grid-gap);
}

@media (min-width: 768px) {
  .features-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.feature-sheet-card {
  background: var(--color-white);
  border: 1px solid var(--color-navy);
  padding: 28px 24px;
  position: relative;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  display: flex;
  flex-direction: column;
}

.feature-sheet-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 10px 24px rgba(48, 73, 102, 0.09);
}

.feature-tag {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-rust);
  font-weight: bold;
  letter-spacing: 0.08em;
  margin-bottom: 12px;
  display: block;
}

.feature-icon-box {
  width: 48px;
  height: 48px;
  border: 1px solid var(--color-navy);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
  background: var(--color-concrete-light);
  color: var(--color-navy);
}

.feature-desc {
  font-size: 15px;
  color: var(--color-text-muted);
  line-height: 1.68;
}

/* Node Floor Plan Section */
.node-plan-wrapper {
  background: var(--color-white);
  border: 1px solid var(--color-navy);
  padding: 24px;
  margin-top: 32px;
}

.node-plan-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}

@media (min-width: 768px) {
  .node-plan-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .node-plan-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.node-room-card {
  border: 1px dashed var(--color-navy);
  padding: 16px;
  background: var(--color-concrete-light);
  position: relative;
}

.node-room-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 8px;
}

.node-room-title {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: bold;
  color: var(--color-navy);
}

.node-room-status {
  width: 8px;
  height: 8px;
  background-color: var(--color-rust);
  border-radius: 50%;
  display: inline-block;
}

.node-room-desc {
  font-size: 13px;
  color: var(--color-text-muted);
  line-height: 1.5;
}

/* AI & Streaming Scenarios Section */
.scenario-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

@media (min-width: 768px) {
  .scenario-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .scenario-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

.scenario-card {
  background: var(--color-white);
  border: 1px solid var(--color-concrete-border);
  padding: 24px;
  position: relative;
  border-top: 3px solid var(--color-navy);
}

.scenario-card.highlight {
  border-top-color: var(--color-rust);
}

.scenario-target {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-rust);
  letter-spacing: 0.05em;
  margin-bottom: 8px;
  display: block;
}

.scenario-title {
  font-size: 20px;
  margin-bottom: 12px;
}

.scenario-body {
  font-size: 15px;
  color: var(--color-text-muted);
  line-height: 1.65;
  margin-bottom: 16px;
}

.scenario-pill-list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.scenario-pill {
  font-family: var(--font-mono);
  font-size: 11px;
  padding: 2px 8px;
  background: var(--color-concrete);
  border: 1px solid var(--color-concrete-border);
  color: var(--color-navy);
}

/* Pricing Section */
.pricing-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
  margin-top: 36px;
}

@media (min-width: 640px) {
  .pricing-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .pricing-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.pricing-card {
  background: var(--color-white);
  border: 1px solid var(--color-navy);
  padding: 32px 24px;
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.pricing-card.recommended {
  border: 2px solid var(--color-rust);
  box-shadow: 0 12px 28px rgba(168, 117, 96, 0.12);
}

.recommend-badge {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--color-rust);
  color: var(--color-white);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: bold;
  padding: 4px 14px;
  letter-spacing: 0.06em;
  white-space: nowrap;
}

.pricing-tier-name {
  font-family: var(--font-mono);
  font-size: 18px;
  font-weight: bold;
  color: var(--color-navy);
  margin-bottom: 8px;
}

.pricing-price-box {
  margin: 16px 0 20px 0;
  padding-bottom: 16px;
  border-bottom: 1px dashed var(--color-concrete-border);
}

.pricing-price {
  font-family: var(--font-serif);
  font-size: 34px;
  font-weight: bold;
  color: var(--color-navy);
}

.pricing-period {
  font-size: 14px;
  color: var(--color-text-muted);
}

.pricing-notice {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--color-rust);
  display: block;
  margin-top: 4px;
}

.pricing-features {
  list-style: none;
  margin-bottom: 28px;
  flex: 1;
}

.pricing-features li {
  font-size: 14px;
  color: var(--color-text-main);
  padding: 8px 0;
  border-bottom: 1px solid var(--color-concrete-light);
  display: flex;
  align-items: center;
  gap: 8px;
}

.pricing-features li::before {
  content: "+";
  font-family: var(--font-mono);
  color: var(--color-rust);
  font-weight: bold;
}

/* Articles Section: 3 / 2 / 1 Grid */
.articles-grid {
  display: grid;
  grid-template-columns: 1fr; /* Mobile 1 col */
  gap: 28px;
  margin-top: 36px;
}

@media (min-width: 640px) {
  .articles-grid {
    grid-template-columns: repeat(2, 1fr); /* Tablet 2 col */
  }
}

@media (min-width: 1024px) {
  .articles-grid {
    grid-template-columns: repeat(3, 1fr); /* Desktop 3 col */
  }
}

.article-sheet-card {
  background: var(--color-white);
  border: 1px solid var(--color-navy);
  position: relative;
  display: flex;
  flex-direction: column;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  overflow: hidden;
}

.article-sheet-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 24px rgba(48, 73, 102, 0.08);
}

.article-card-header {
  border-bottom: 1px solid var(--color-navy);
  padding: 10px 16px;
  background: var(--color-concrete-light);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 11px;
}

.article-card-body {
  padding: 24px 20px;
  flex: 1;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.article-card-title {
  font-size: 20px;
  line-height: 1.4;
  margin-bottom: 12px;
}

.article-card-title a {
  color: var(--color-navy);
}

.article-card-title a:hover {
  color: var(--color-rust);
}

.article-card-excerpt {
  font-size: 14px;
  color: var(--color-text-muted);
  line-height: 1.65;
  margin-bottom: 20px;
  flex: 1;
}

.article-card-footer {
  border-top: 1px dashed var(--color-concrete-border);
  padding-top: 14px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 12px;
}

/* Testimonials Section */
.testimonials-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

@media (min-width: 768px) {
  .testimonials-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .testimonials-grid {
    grid-template-columns: repeat(4, 1fr);
  }
}

.testimonial-card {
  background: var(--color-white);
  border: 1px solid var(--color-concrete-border);
  border-left: 3px solid var(--color-navy);
  padding: 20px;
}

.testimonial-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 12px;
  font-family: var(--font-mono);
  font-size: 11px;
}

.testimonial-quote {
  font-size: 14px;
  color: var(--color-text-main);
  line-height: 1.65;
  font-style: italic;
  margin-bottom: 12px;
}

.testimonial-author {
  font-size: 13px;
  font-weight: bold;
  color: var(--color-navy);
}

.testimonial-role {
  font-size: 11px;
  color: var(--color-text-muted);
  font-family: var(--font-mono);
}

/* FAQ Accordion Section */
.faq-list {
  max-width: 860px;
  margin: 0 auto;
}

.faq-item {
  border: 1px solid var(--color-navy);
  margin-bottom: 16px;
  background: var(--color-white);
}

.faq-question {
  width: 100%;
  text-align: left;
  padding: 18px 24px;
  font-family: var(--font-serif);
  font-size: 18px;
  font-weight: bold;
  color: var(--color-navy);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
}

.faq-question:hover {
  background-color: var(--color-concrete-light);
}

.faq-indicator {
  font-family: var(--font-mono);
  font-size: 18px;
  color: var(--color-rust);
  font-weight: normal;
  transition: transform 0.2s ease;
}

.faq-item.active .faq-indicator {
  transform: rotate(45deg);
}

.faq-answer {
  display: none;
  padding: 0 24px 20px 24px;
  font-size: 15px;
  color: var(--color-text-muted);
  line-height: 1.7;
  border-top: 1px dashed var(--color-concrete);
}

.faq-item.active .faq-answer {
  display: block;
  padding-top: 16px;
}

/* Site Footer */
.site-footer {
  background-color: var(--color-navy-dark);
  color: #C3D0DE;
  padding-top: 64px;
  padding-bottom: 40px;
  border-top: 3px solid var(--color-rust);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 40px;
  margin-bottom: 48px;
}

@media (min-width: 640px) {
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 992px) {
  .footer-grid {
    grid-template-columns: 1.4fr 1fr 1fr 1fr;
  }
}

.footer-brand-title {
  color: var(--color-white);
  font-family: var(--font-serif);
  font-size: 22px;
  margin-bottom: 12px;
}

.footer-brand-desc {
  font-size: 14px;
  line-height: 1.65;
  color: #97AEC4;
  margin-bottom: 20px;
}

.footer-heading {
  font-family: var(--font-mono);
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-white);
  margin-bottom: 16px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.15);
  padding-bottom: 8px;
}

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

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

.footer-links a {
  color: #C3D0DE;
  font-size: 14px;
  transition: color 0.2s ease;
}

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

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 28px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  align-items: center;
  text-align: center;
  font-family: var(--font-mono);
  font-size: 12px;
  color: #839BB3;
}

@media (min-width: 768px) {
  .footer-bottom {
    flex-direction: row;
    justify-content: space-between;
    text-align: left;
  }
}

.footer-disclaimer {
  max-width: 800px;
  font-size: 11px;
  color: #728A9E;
  margin-top: 8px;
  line-height: 1.5;
}

/* Article Detail Page Specific Styles */
.article-header {
  padding-top: 48px;
  padding-bottom: 36px;
  border-bottom: 1px solid var(--color-concrete-border);
  background: var(--color-concrete-light);
}

.breadcrumb-nav {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  margin-bottom: 20px;
}

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

.breadcrumb-nav span {
  color: var(--color-rust);
}

.article-meta-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 20px;
  margin-top: 20px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-text-muted);
}

.article-content-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 48px;
  padding-top: 48px;
  padding-bottom: 64px;
}

@media (min-width: 1024px) {
  .article-content-layout {
    grid-template-columns: 1fr 320px;
  }
}

.article-main-body {
  font-size: 17px;
  line-height: 1.85;
  color: var(--color-text-main);
}

.article-main-body h2 {
  margin-top: 40px;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--color-concrete);
  padding-bottom: 8px;
  display: block;
}

.article-main-body h3 {
  margin-top: 28px;
  margin-bottom: 12px;
}

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

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

.article-main-body blockquote {
  border-left: 3px solid var(--color-rust);
  padding: 16px 20px;
  background: var(--color-concrete-light);
  margin: 24px 0;
  font-style: italic;
}

.article-main-body code {
  font-family: var(--font-mono);
  font-size: 14px;
  background: var(--color-concrete);
  padding: 2px 6px;
  border: 1px solid var(--color-concrete-border);
}

.article-main-body pre {
  background: var(--color-navy-dark);
  color: var(--color-white);
  padding: 16px;
  font-family: var(--font-mono);
  font-size: 13px;
  overflow-x: auto;
  margin: 20px 0;
  border: 1px solid var(--color-navy);
}

.article-sidebar {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.sidebar-box {
  background: var(--color-white);
  border: 1px solid var(--color-navy);
  padding: 24px;
}

.sidebar-title {
  font-family: var(--font-serif);
  font-size: 18px;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--color-concrete);
  padding-bottom: 8px;
}

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

.related-list li {
  margin-bottom: 12px;
  padding-bottom: 12px;
  border-bottom: 1px dashed var(--color-concrete);
}

.related-list a {
  font-size: 14px;
  line-height: 1.5;
  display: block;
}

/* Page Intro Block (for About, Terms, Privacy, Sitemap, Tutorial) */
.page-intro-sheet {
  background: var(--color-white);
  border: 1px solid var(--color-navy);
  padding: 32px;
  margin-bottom: 40px;
}

@media (min-width: 768px) {
  .page-intro-sheet {
    padding: 48px;
  }
}