/* ==========================================================================
   山水云机场 · 第2套独立中文网站
   视觉主题：留白院落系统（中央留白 + 四周内容围合 + 空间层次）
   ========================================================================== */

:root {
  --bg: #FAF9F5;
  --surface: #FFFFFF;
  --surface-alt: #F1EFE9;
  --text: #202627;
  --body: #5E6566;
  --muted: #8A9091;
  --blue: #435D63;
  --blue-dark: #334A50;
  --green: #5B6D64;
  --green-dark: #48574F;
  --stone: #9E795D;
  --warm: #AD6F54;
  --tint-blue: #EEF1F1;
  --tint-green: #EFF2EF;
  --tint-sand: #F5EEE7;
  --border: #DFDDD6;
  --footer-text: #4C5556;
  --shadow-subtle: 0 10px 28px rgba(32, 38, 39, 0.02);
  --radius-sm: 4px;
  --max-width: 1280px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
}

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

html {
  font-size: 16px;
  scroll-behavior: smooth;
  background-color: var(--bg);
  color: var(--body);
  font-family: var(--font-sans);
  -webkit-text-size-adjust: 100%;
}

body {
  background-color: var(--bg);
  color: var(--body);
  font-family: var(--font-sans);
  font-size: 17px;
  line-height: 1.86;
  font-weight: 400;
  overflow-x: hidden;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1 0 auto;
}

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

a {
  color: var(--text);
  text-decoration: none;
  transition: color 0.18s ease, border-color 0.18s ease, background-color 0.18s ease;
}

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

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

/* Focus-visible Accessibility (Rule 256) */
a:focus-visible,
button:focus-visible,
summary:focus-visible,
[tabindex]:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 3px;
  border-radius: 2px;
}

/* Typography Scale (Rules 20-21) */
h1, h2, h3, h4 {
  color: var(--text);
  font-weight: 600;
  letter-spacing: -0.01em;
}

h1 {
  font-size: 48px;
  line-height: 1.24;
  font-weight: 600;
}

h2 {
  font-size: 32px;
  line-height: 1.32;
  font-weight: 600;
}

h3 {
  font-size: 22px;
  line-height: 1.42;
  font-weight: 600;
}

p {
  margin-bottom: 1rem;
}

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

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 28px;
}

/* ==========================================================================
   Header & Navigation (Rules 25-28)
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: 70px;
  background-color: var(--bg);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  max-width: var(--max-width);
  height: 100%;
  margin: 0 auto;
  padding: 0 28px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand-link {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--text);
  flex-shrink: 0;
}

.brand-link:hover {
  color: var(--text);
}

.brand-logo {
  width: 34px;
  height: 34px;
  flex-shrink: 0;
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.brand-name {
  font-size: 17px;
  font-weight: 600;
  color: var(--text);
  letter-spacing: 0.02em;
}

.brand-sub {
  font-size: 11.5px;
  color: var(--muted);
  margin-top: 2px;
  letter-spacing: 0.03em;
}

.desktop-nav {
  display: flex;
  align-items: center;
  gap: 20px;
}

.nav-link {
  position: relative;
  font-size: 14.5px;
  color: var(--body);
  padding: 6px 0;
  white-space: nowrap;
}

.nav-link:hover {
  color: var(--text);
}

.nav-link.is-active {
  color: var(--text);
  font-weight: 600;
}

.nav-link.is-active::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: -2px;
  transform: translateX(-50%);
  width: 20px;
  height: 1.5px;
  background-color: var(--text);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-shrink: 0;
}

.btn-header-cta {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  font-size: 14px;
  font-weight: 500;
  color: var(--surface);
  background-color: var(--blue);
  border: 1px solid var(--blue);
  border-radius: var(--radius-sm);
}

.btn-header-cta:hover {
  background-color: var(--blue-dark);
  border-color: var(--blue-dark);
  color: var(--surface);
}

.btn-header-cta .arrow,
.btn-primary .arrow,
.text-link .arrow,
.boundary-link .arrow {
  display: inline-block;
  transition: transform 0.18s ease;
}

.btn-header-cta:hover .arrow,
.btn-primary:hover .arrow,
.text-link:hover .arrow,
.boundary-link:hover .arrow {
  transform: translateX(3px);
}

.mobile-menu-btn {
  display: none;
  align-items: center;
  gap: 6px;
  padding: 7px 14px;
  font-size: 14px;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background-color: var(--surface);
}

.mobile-nav-drawer {
  display: none;
  background-color: var(--bg);
  border-bottom: 1px solid var(--border);
  padding: 16px 28px 24px;
}

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

.mobile-nav-list {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px 16px;
  margin-bottom: 16px;
}

.mobile-nav-list a {
  display: block;
  padding: 8px 10px;
  font-size: 15px;
  color: var(--text);
  border-bottom: 1px solid var(--border);
}

/* ==========================================================================
   Buttons & Links
   ========================================================================== */
.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 24px;
  font-size: 15px;
  font-weight: 500;
  color: var(--surface);
  background-color: var(--blue);
  border: 1px solid var(--blue);
  border-radius: var(--radius-sm);
}

.btn-primary:hover {
  background-color: var(--blue-dark);
  border-color: var(--blue-dark);
  color: var(--surface);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 11px 22px;
  font-size: 15px;
  font-weight: 500;
  color: var(--text);
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

.btn-secondary:hover {
  border-color: var(--blue);
  color: var(--blue);
}

.text-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 14.5px;
  font-weight: 500;
  color: var(--blue);
  border-bottom: 1px solid transparent;
}

.text-link:hover {
  color: var(--blue-dark);
  border-bottom-color: var(--blue-dark);
}

.boundary-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 13.5px;
  font-weight: 500;
  color: var(--blue);
}

.boundary-link:hover {
  color: var(--blue-dark);
}

/* ==========================================================================
   Hero: 中央留白院落 (Rules 29-49, 260-261)
   ========================================================================== */
.hero-section {
  padding: 24px 0 36px;
}

.courtyard-hero {
  position: relative;
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-subtle);
  min-height: 680px;
  max-height: 750px;
  display: grid;
  grid-template-columns: 220px 1fr 220px;
  grid-template-rows: auto 1fr auto;
  grid-template-areas:
    "top top top"
    "left center right"
    "bottom bottom bottom";
}

/* Intentional architectural opening on outer border (36px gap, Rule 43) */
.courtyard-hero::before {
  content: "";
  position: absolute;
  top: -2px;
  right: 56px;
  width: 36px;
  height: 4px;
  background-color: var(--bg);
  z-index: 2;
  pointer-events: none;
}

.courtyard-hero::after {
  content: "";
  position: absolute;
  top: -4px;
  right: 92px;
  width: 1px;
  height: 7px;
  background-color: var(--border);
  z-index: 3;
  pointer-events: none;
}

/* Hero Top Boundary (Rule 37) */
.hero-top {
  grid-area: top;
  position: relative;
  padding: 15px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  background-color: var(--bg);
}

.hero-top::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 32px;
  right: 32px;
  height: 1px;
  background-color: var(--border);
}

.boundary-bar-group {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 14px 24px;
}

.boundary-label {
  font-size: 13px;
  font-weight: 600;
  color: var(--text);
  letter-spacing: 0.04em;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.boundary-label::before {
  content: "";
  width: 6px;
  height: 6px;
  border: 1px solid var(--stone);
  display: inline-block;
}

.boundary-items-inline {
  list-style: none;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px 20px;
}

.boundary-items-inline li {
  font-size: 14px;
  color: var(--body);
  position: relative;
}

.boundary-items-inline li + li::before {
  content: "·";
  margin-right: 20px;
  color: var(--muted);
}

/* Hero Left Boundary (Rule 38) */
.hero-left {
  grid-area: left;
  position: relative;
  padding: 36px 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.hero-left::after {
  content: "";
  position: absolute;
  top: 32px;
  bottom: 32px;
  right: 0;
  width: 1px;
  background-color: var(--border);
}

/* Hero Right Boundary (Rule 39) */
.hero-right {
  grid-area: right;
  position: relative;
  padding: 36px 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.hero-right::before {
  content: "";
  position: absolute;
  top: 32px;
  bottom: 32px;
  left: 0;
  width: 1px;
  background-color: var(--border);
}

.boundary-stack-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin: 20px 0;
}

.boundary-stack-list li {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--tint-blue);
  font-size: 14.5px;
  color: var(--text);
}

.boundary-stack-list li span {
  font-size: 12.5px;
  color: var(--muted);
}

.boundary-note {
  font-size: 13px;
  color: var(--muted);
  line-height: 1.65;
  margin-bottom: 16px;
}

/* Hero Center Courtyard Core (Rules 32-36, 42) */
.hero-center {
  grid-area: center;
  padding: 38px 56px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  background-color: var(--surface);
}

.hero-kicker {
  font-size: 13px;
  color: var(--stone);
  letter-spacing: 0.08em;
  margin-bottom: 10px;
}

.hero-brand-title {
  font-size: 58px;
  line-height: 1.12;
  font-weight: 600;
  color: var(--text);
  letter-spacing: 0.02em;
  margin-bottom: 12px;
}

.hero-lead {
  font-size: 21px;
  line-height: 1.5;
  color: var(--green-dark);
  font-weight: 500;
  margin-bottom: 18px;
}

.hero-h1 {
  font-size: 46px;
  line-height: 1.22;
  font-weight: 600;
  color: var(--text);
  max-width: 720px;
  margin-bottom: 16px;
}

.hero-desc {
  font-size: 16.5px;
  line-height: 1.82;
  color: var(--body);
  max-width: 620px;
  margin-bottom: 26px;
}

.hero-cta-group {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 14px 20px;
}

/* Hero Bottom Boundary (Rule 40) */
.hero-bottom {
  grid-area: bottom;
  position: relative;
  padding: 15px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  background-color: var(--bg);
}

.hero-bottom::before {
  content: "";
  position: absolute;
  top: 0;
  left: 32px;
  right: 32px;
  height: 1px;
  background-color: var(--border);
}

/* ==========================================================================
   Section Common Layout (Rule 51)
   ========================================================================== */
.site-section {
  padding: 56px 0;
}

.site-section + .site-section {
  border-top: 1px solid rgba(223, 221, 214, 0.55);
}

.section-header {
  max-width: 780px;
  margin-bottom: 32px;
}

.section-meta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 12.5px;
  color: var(--stone);
  letter-spacing: 0.06em;
  margin-bottom: 8px;
}

.section-title {
  font-size: 31px;
  line-height: 1.32;
  color: var(--text);
  margin-bottom: 12px;
}

.section-direct-answer {
  font-size: 17px;
  line-height: 1.85;
  color: var(--body);
}

/* ==========================================================================
   Shared Courtyard Frame System (Rules 7, 8, 10, 60-69)
   ========================================================================== */
.courtyard-frame {
  position: relative;
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

/* Subtle unclosed frame motif on courtyard containers */
.courtyard-frame::before {
  content: "";
  position: absolute;
  bottom: -2px;
  left: 48px;
  width: 32px;
  height: 4px;
  background-color: var(--bg);
  pointer-events: none;
}

/* Five-Zone Courtyard Grid (Top / Left / Center / Right / Bottom) */
.courtyard-five-grid {
  display: grid;
  grid-template-columns: 270px 1fr 270px;
  grid-template-rows: auto 1fr auto;
  grid-template-areas:
    "c-top c-top c-top"
    "c-left c-center c-right"
    "c-bottom c-bottom c-bottom";
}

.c-zone-top {
  grid-area: c-top;
  position: relative;
  padding: 24px 36px;
  background-color: var(--bg);
}

.c-zone-top::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 32px;
  right: 32px;
  height: 1px;
  background-color: var(--border);
}

.c-zone-left {
  grid-area: c-left;
  position: relative;
  padding: 32px 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.c-zone-left::after {
  content: "";
  position: absolute;
  top: 28px;
  bottom: 28px;
  right: 0;
  width: 1px;
  background-color: var(--border);
}

.c-zone-center {
  grid-area: c-center;
  padding: 44px 48px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.c-zone-right {
  grid-area: c-right;
  position: relative;
  padding: 32px 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.c-zone-right::before {
  content: "";
  position: absolute;
  top: 28px;
  bottom: 28px;
  left: 0;
  width: 1px;
  background-color: var(--border);
}

.c-zone-bottom {
  grid-area: c-bottom;
  position: relative;
  padding: 24px 36px;
  background-color: var(--bg);
}

.c-zone-bottom::before {
  content: "";
  position: absolute;
  top: 0;
  left: 32px;
  right: 32px;
  height: 1px;
  background-color: var(--border);
}

/* ==========================================================================
   Section 01 & 06: 围合价目 (Plan & Pricing Courtyard - Rules 52-72, 117-128)
   ========================================================================== */
.plan-zone-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px 28px;
}

.plan-zone-meta {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 12px 24px;
}

.plan-name {
  font-size: 19px;
  font-weight: 600;
  color: var(--text);
}

.plan-quota {
  font-size: 15px;
  font-weight: 500;
  color: var(--green-dark);
  padding: 2px 10px;
  background-color: var(--tint-green);
  border-radius: 2px;
}

.plan-price {
  font-size: 31px;
  font-weight: 600;
  color: var(--text);
  line-height: 1.2;
}

.plan-price small {
  font-size: 14px;
  font-weight: 400;
  color: var(--muted);
}

.plan-fit {
  font-size: 14.5px;
  color: var(--body);
}

/* Main Recommended Plan in Center (Rules 61, 68, 119) */
.plan-center-featured {
  background-color: var(--tint-green);
  align-items: center;
  text-align: center;
}

.plan-badge {
  display: inline-block;
  padding: 3px 12px;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--surface);
  background-color: var(--green);
  border-radius: 2px;
  letter-spacing: 0.05em;
  margin-bottom: 12px;
}

.plan-center-featured .plan-name {
  font-size: 26px;
  margin-bottom: 6px;
}

.plan-center-featured .plan-price {
  font-size: 38px;
  color: var(--text);
  margin: 8px 0;
}

.plan-center-featured .plan-quota-main {
  font-size: 18px;
  font-weight: 600;
  color: var(--green-dark);
  margin-bottom: 12px;
}

.plan-center-featured .plan-fit {
  font-size: 15.5px;
  color: var(--text);
  max-width: 440px;
  margin-bottom: 22px;
}

.plan-side-stack {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

/* ==========================================================================
   Section 02 & 03: 节点地区与线路理解 (Rules 73-95)
   ========================================================================== */
.courtyard-center-box {
  max-width: 560px;
  margin: 0 auto;
  text-align: center;
}

.courtyard-center-kicker {
  font-size: 12.5px;
  color: var(--stone);
  letter-spacing: 0.06em;
  margin-bottom: 8px;
}

.courtyard-center-title {
  font-size: 26px;
  color: var(--text);
  margin-bottom: 14px;
}

.courtyard-center-desc {
  font-size: 16.5px;
  color: var(--body);
  line-height: 1.85;
  margin-bottom: 20px;
}

.region-title {
  font-size: 19px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.region-tag {
  font-size: 12px;
  font-weight: 400;
  color: var(--muted);
}

.region-desc {
  font-size: 15px;
  color: var(--body);
  line-height: 1.8;
}

.line-point-list {
  list-style: none;
  margin-top: 10px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.line-point-list li {
  font-size: 14px;
  color: var(--body);
}

.line-point-list strong {
  color: var(--text);
  font-weight: 600;
}

/* HTML Comparison Table (Rules 92-93, 273-274) */
.table-section-wrap {
  margin-top: 28px;
  background-color: var(--surface);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  padding: 20px 28px;
}

.table-caption {
  font-size: 14px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 12px;
}

.minimal-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

.minimal-table th {
  font-size: 13.5px;
  font-weight: 600;
  color: var(--text);
  padding: 12px 16px 12px 0;
  border-bottom: 1px solid var(--border);
}

.minimal-table td {
  font-size: 15px;
  color: var(--body);
  padding: 14px 16px 14px 0;
  border-bottom: 1px solid rgba(223, 221, 214, 0.65);
  vertical-align: top;
}

.minimal-table tbody tr:last-child td {
  border-bottom: none;
}

/* ==========================================================================
   Section 04: AI与流媒体围合 (Rules 96-106)
   ========================================================================== */
.ai-media-courtyard {
  display: grid;
  grid-template-columns: 1fr 340px 1fr;
  grid-template-rows: auto 1fr auto;
  grid-template-areas:
    "am-top am-top am-top"
    "am-left am-center am-right"
    "am-bottom am-bottom am-bottom";
}

.am-zone-top {
  grid-area: am-top;
  position: relative;
  padding: 22px 36px;
  background-color: var(--bg);
}

.am-zone-top::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 32px;
  right: 32px;
  height: 1px;
  background-color: var(--border);
}

.am-zone-left {
  grid-area: am-left;
  position: relative;
  padding: 34px 36px;
}

.am-zone-left::after {
  content: "";
  position: absolute;
  top: 28px;
  bottom: 28px;
  right: 0;
  width: 1px;
  background-color: var(--border);
}

.am-zone-center {
  grid-area: am-center;
  padding: 38px 32px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  text-align: center;
  background-color: var(--tint-sand);
}

.am-zone-right {
  grid-area: am-right;
  position: relative;
  padding: 34px 36px;
}

.am-zone-right::before {
  content: "";
  position: absolute;
  top: 28px;
  bottom: 28px;
  left: 0;
  width: 1px;
  background-color: var(--border);
}

.am-zone-bottom {
  grid-area: am-bottom;
  position: relative;
  padding: 20px 36px;
  background-color: var(--bg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
}

.am-zone-bottom::before {
  content: "";
  position: absolute;
  top: 0;
  left: 32px;
  right: 32px;
  height: 1px;
  background-color: var(--border);
}

.platform-group-label {
  font-size: 13px;
  font-weight: 600;
  color: var(--stone);
  margin: 16px 0 8px;
}

.platform-primary-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.platform-primary-list li {
  padding-bottom: 10px;
  border-bottom: 1px solid var(--tint-blue);
  font-size: 15px;
  color: var(--body);
}

.platform-primary-list strong {
  color: var(--text);
  font-weight: 600;
  margin-right: 8px;
}

.platform-secondary-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 8px;
}

.platform-tag {
  font-size: 13.5px;
  color: var(--text);
  padding: 4px 12px;
  background-color: var(--bg);
  border: 1px solid var(--border);
  border-radius: 2px;
}

/* ==========================================================================
   Section 05: 客户端围合 (Rules 107-116)
   ========================================================================== */
.ops-strip {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px 14px;
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid var(--border);
}

.ops-pill {
  font-size: 13.5px;
  color: var(--text);
  padding: 4px 12px;
  background-color: var(--bg);
  border: 1px solid var(--border);
  border-radius: 2px;
}

/* ==========================================================================
   Section 08: 内容院落 (Content Courtyard - Rules 137-145)
   ========================================================================== */
.content-courtyard {
  display: grid;
  grid-template-columns: 290px 1fr 290px;
  grid-template-rows: auto 1fr auto;
  grid-template-areas:
    "cc-top cc-top cc-top"
    "cc-left cc-center cc-right"
    "cc-bottom cc-bottom cc-bottom";
}

.cc-top {
  grid-area: cc-top;
  position: relative;
  padding: 26px 36px;
  background-color: var(--bg);
}

.cc-top::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 32px;
  right: 32px;
  height: 1px;
  background-color: var(--border);
}

.cc-left {
  grid-area: cc-left;
  position: relative;
  padding: 32px 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.cc-left::after {
  content: "";
  position: absolute;
  top: 28px;
  bottom: 28px;
  right: 0;
  width: 1px;
  background-color: var(--border);
}

.cc-center {
  grid-area: cc-center;
  padding: 44px 48px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  background-color: var(--surface);
}

.cc-right {
  grid-area: cc-right;
  position: relative;
  padding: 32px 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.cc-right::before {
  content: "";
  position: absolute;
  top: 28px;
  bottom: 28px;
  left: 0;
  width: 1px;
  background-color: var(--border);
}

.cc-bottom {
  grid-area: cc-bottom;
  position: relative;
  padding: 24px 36px;
  background-color: var(--bg);
}

.cc-bottom::before {
  content: "";
  position: absolute;
  top: 0;
  left: 32px;
  right: 32px;
  height: 1px;
  background-color: var(--border);
}

.article-meta-line {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px 16px;
  font-size: 13px;
  color: var(--muted);
  margin-bottom: 10px;
}

.article-cat-badge {
  color: var(--blue);
  font-weight: 600;
}

.cc-center-title {
  font-size: 28px;
  line-height: 1.34;
  margin-bottom: 14px;
}

.cc-center-title a {
  color: var(--text);
}

.cc-center-title a:hover {
  color: var(--blue);
}

.cc-top-title {
  font-size: 21px;
  line-height: 1.38;
  margin-bottom: 8px;
}

.cc-side-title {
  font-size: 18.5px;
  line-height: 1.42;
  margin-bottom: 10px;
}

.compact-article-rows {
  list-style: none;
  display: flex;
  flex-direction: column;
}

.compact-article-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 12px 0;
  border-bottom: 1px solid rgba(223, 221, 214, 0.7);
}

.compact-article-row:last-child {
  border-bottom: none;
  padding-bottom: 0;
}

.compact-row-main {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 8px 16px;
}

.compact-row-title {
  font-size: 15.5px;
  font-weight: 500;
  color: var(--text);
}

.compact-row-title:hover {
  color: var(--blue);
}

.category-strip-bar {
  margin-top: 20px;
  padding: 16px 24px;
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px 24px;
}

.category-links-inline {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px 24px;
}

/* ==========================================================================
   Section 09: 网络排障围合 (Troubleshooting Courtyard - Rules 153-166)
   ========================================================================== */
.trouble-sub-split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
}

.trouble-item-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 6px;
}

.trouble-item-title.is-secondary {
  font-size: 16.5px;
}

.trouble-item-desc {
  font-size: 14.5px;
  color: var(--body);
  line-height: 1.78;
}

/* ==========================================================================
   Section 10: 常见问题围合 (FAQ Courtyard - Rules 167-172)
   ========================================================================== */
.faq-courtyard {
  display: grid;
  grid-template-columns: 1fr 300px 1fr;
  grid-template-rows: auto auto auto;
  grid-template-areas:
    "fq-top fq-top fq-top"
    "fq-left fq-center fq-right"
    "fq-bottom-left fq-bottom-left fq-bottom-right";
}

.fq-top {
  grid-area: fq-top;
  position: relative;
  padding: 26px 36px;
  background-color: var(--bg);
}

.fq-top::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 32px;
  right: 32px;
  height: 1px;
  background-color: var(--border);
}

.fq-left {
  grid-area: fq-left;
  position: relative;
  padding: 30px 32px;
}

.fq-left::after {
  content: "";
  position: absolute;
  top: 28px;
  bottom: 28px;
  right: 0;
  width: 1px;
  background-color: var(--border);
}

.fq-center {
  grid-area: fq-center;
  padding: 36px 28px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  text-align: center;
  background-color: var(--tint-blue);
}

.fq-right {
  grid-area: fq-right;
  position: relative;
  padding: 30px 32px;
}

.fq-right::before {
  content: "";
  position: absolute;
  top: 28px;
  bottom: 28px;
  left: 0;
  width: 1px;
  background-color: var(--border);
}

.fq-bottom-left {
  grid-area: fq-bottom-left;
  position: relative;
  padding: 28px 36px;
  background-color: var(--bg);
}

.fq-bottom-left::before {
  content: "";
  position: absolute;
  top: 0;
  left: 32px;
  right: 0;
  height: 1px;
  background-color: var(--border);
}

.fq-bottom-right {
  grid-area: fq-bottom-right;
  position: relative;
  padding: 28px 32px;
  background-color: var(--bg);
}

.fq-bottom-right::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 32px;
  height: 1px;
  background-color: var(--border);
}

.fq-bottom-right::after {
  content: "";
  position: absolute;
  top: 24px;
  bottom: 24px;
  left: 0;
  width: 1px;
  background-color: var(--border);
}

.faq-group-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.faq-group-title span {
  font-size: 12px;
  color: var(--stone);
  font-weight: 500;
}

.faq-list {
  display: flex;
  flex-direction: column;
}

.faq-list-grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0 32px;
}

.faq-item {
  border-bottom: 1px solid rgba(223, 221, 214, 0.75);
}

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

.faq-trigger {
  width: 100%;
  padding: 12px 0;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  text-align: left;
  font-size: 15px;
  font-weight: 500;
  color: var(--text);
}

.faq-trigger:hover {
  color: var(--blue);
}

.faq-q-left {
  display: flex;
  align-items: baseline;
  gap: 10px;
}

.faq-num {
  font-size: 12.5px;
  font-weight: 600;
  color: var(--stone);
  flex-shrink: 0;
}

.faq-icon {
  font-size: 16px;
  color: var(--muted);
  flex-shrink: 0;
  transition: transform 0.18s ease;
}

.faq-trigger[aria-expanded="true"] .faq-icon {
  transform: rotate(45deg);
  color: var(--blue);
}

.faq-answer {
  padding: 0 0 14px 34px;
  font-size: 14.5px;
  line-height: 1.82;
  color: var(--body);
}

/* Progressive enhancement: only collapse when JS is active (Rule 205, 282) */
.js-enabled .faq-item[data-collapsed="true"] .faq-answer {
  display: none;
}

/* ==========================================================================
   Category Pages (Rules 146-152)
   ========================================================================== */
.breadcrumb-nav {
  padding: 20px 0 12px;
  font-size: 13.5px;
  color: var(--muted);
}

.breadcrumb-list {
  list-style: none;
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
}

.breadcrumb-list a {
  color: var(--body);
}

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

.category-hero {
  position: relative;
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  min-height: 240px;
  max-height: 310px;
  margin-bottom: 36px;
  display: grid;
  grid-template-columns: 220px 1fr 220px;
  align-items: stretch;
}

.category-hero-side {
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  background-color: var(--bg);
}

.category-hero-side.is-left {
  border-right: 1px solid var(--border);
}

.category-hero-side.is-right {
  border-left: 1px solid var(--border);
}

.category-hero-center {
  padding: 32px 40px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
}

.category-hero-center h1 {
  font-size: 38px;
  margin-bottom: 12px;
}

.category-intro {
  font-size: 16px;
  color: var(--body);
  max-width: 640px;
  line-height: 1.82;
}

.category-featured-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  margin-bottom: 28px;
}

.category-featured-item {
  padding: 28px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.category-featured-item + .category-featured-item {
  border-left: 1px solid var(--border);
}

.category-standard-list {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 8px 32px;
  margin-bottom: 48px;
}

.category-list-item {
  padding: 24px 0;
  border-bottom: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

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

/* ==========================================================================
   Article Pages (Rules 173-183)
   ========================================================================== */
.article-hero-enclosure {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  margin-bottom: 28px;
  display: grid;
  grid-template-columns: 190px 1fr 190px;
}

.article-hero-meta-side {
  padding: 24px 20px;
  background-color: var(--bg);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  font-size: 13px;
  color: var(--muted);
}

.article-hero-meta-side.is-left {
  border-right: 1px solid var(--border);
}

.article-hero-meta-side.is-right {
  border-left: 1px solid var(--border);
}

.article-hero-center {
  padding: 36px 44px;
}

.article-hero-center h1 {
  font-size: 36px;
  line-height: 1.3;
  margin-bottom: 14px;
}

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

.article-layout {
  display: grid;
  grid-template-columns: minmax(0, 800px) 230px;
  justify-content: space-between;
  align-items: start;
  gap: 36px;
  margin-bottom: 56px;
}

.article-main {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 44px 48px;
  max-width: 800px;
}

.quick-conclusion {
  background-color: var(--tint-sand);
  border-left: 3px solid var(--stone);
  padding: 20px 24px;
  margin-bottom: 32px;
}

.quick-conclusion-label {
  font-size: 13px;
  font-weight: 600;
  color: var(--stone);
  letter-spacing: 0.04em;
  margin-bottom: 6px;
}

.quick-conclusion p {
  font-size: 16px;
  color: var(--text);
  line-height: 1.82;
}

.mobile-toc-box {
  display: none;
  background-color: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 18px;
  margin-bottom: 28px;
}

.mobile-toc-box summary {
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  cursor: pointer;
}

.article-content h2 {
  font-size: 26px;
  margin: 36px 0 14px;
  padding-top: 12px;
  border-top: 1px solid rgba(223, 221, 214, 0.55);
}

.article-content h2:first-of-type {
  margin-top: 0;
  padding-top: 0;
  border-top: none;
}

.article-content h3 {
  font-size: 20px;
  margin: 24px 0 10px;
}

.article-content p {
  font-size: 17px;
  line-height: 1.88;
  color: var(--body);
  margin-bottom: 16px;
}

.article-content ul,
.article-content ol {
  margin: 0 0 18px 22px;
  color: var(--body);
}

.article-content li {
  margin-bottom: 8px;
  line-height: 1.82;
}

.article-content a {
  color: var(--blue);
  border-bottom: 1px solid rgba(67, 93, 99, 0.35);
}

.article-content a:hover {
  color: var(--blue-dark);
  border-bottom-color: var(--blue-dark);
}

.article-callout {
  background-color: var(--bg);
  border: 1px solid var(--border);
  padding: 18px 22px;
  margin: 22px 0;
  border-radius: var(--radius-sm);
}

.article-callout-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 6px;
}

.article-sidebar {
  position: sticky;
  top: 90px;
  width: 230px;
}

.toc-panel {
  background-color: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 20px;
  margin-bottom: 20px;
}

.toc-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border);
}

.toc-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
  max-height: 62vh;
  overflow-y: auto;
}

.toc-list a {
  display: block;
  font-size: 13.5px;
  line-height: 1.45;
  color: var(--body);
}

.toc-list a:hover,
.toc-list a.is-active {
  color: var(--blue);
  font-weight: 500;
}

.related-reading-box {
  margin-top: 36px;
  padding-top: 28px;
  border-top: 1px solid var(--border);
}

.related-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 14px;
}

.related-item {
  padding: 16px;
  background-color: var(--bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
}

.article-pager {
  margin-top: 28px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
  font-size: 14.5px;
}

/* ==========================================================================
   Footer (Rules 212-219, 240, 279-280)
   ========================================================================== */
.site-footer {
  background-color: var(--surface-alt);
  color: var(--footer-text);
  border-top: 1px solid var(--border);
  padding: 28px 0 22px;
}

.footer-top-grid {
  display: grid;
  grid-template-columns: 1.35fr 1fr 1fr 1fr 1fr;
  border-bottom: 1px solid var(--border);
  padding-bottom: 20px;
  margin-bottom: 16px;
}

.footer-col {
  padding: 0 20px;
  border-left: 1px solid var(--border);
}

.footer-col:first-child {
  padding-left: 0;
  border-left: none;
}

.footer-col:last-child {
  padding-right: 0;
}

.footer-brand-title {
  font-size: 17px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 4px;
}

.footer-brand-desc {
  font-size: 13px;
  color: var(--footer-text);
  margin-bottom: 12px;
}

.footer-col-title {
  font-size: 13.5px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 8px;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.footer-links a {
  font-size: 13px;
  color: var(--footer-text);
  line-height: 1.55;
}

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

.footer-bottom-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px 24px;
  font-size: 13px;
  color: var(--footer-text);
}

.friend-links {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px 18px;
}

.friend-links a {
  color: var(--footer-text);
  font-size: 13px;
}

.friend-links a:hover {
  color: var(--text);
  text-decoration: underline;
}

/* ==========================================================================
    Responsive Design (Rules 48-49, 72, 94, 128, 166, 172, 232-240, 257, 274)
   ========================================================================== */
@media (max-width: 1120px) {
  .desktop-nav {
    gap: 14px;
  }
  .nav-link {
    font-size: 13.5px;
  }
  .courtyard-hero {
    grid-template-columns: 190px 1fr 190px;
  }
  .hero-center {
    padding: 32px 32px;
  }
  .hero-brand-title {
    font-size: 50px;
  }
  .hero-h1 {
    font-size: 40px;
  }
  .courtyard-five-grid,
  .content-courtyard {
    grid-template-columns: 230px 1fr 230px;
  }
}

@media (max-width: 960px) {
  .desktop-nav {
    display: none;
  }
  .mobile-menu-btn {
    display: inline-flex;
  }
  .brand-sub {
    display: none;
  }

  /* Cancel 4-sided enclosure on Mobile/Tablet & convert to ordered vertical flow */
  .courtyard-hero {
    display: flex;
    flex-direction: column;
    min-height: 0;
    max-height: none;
  }

  /* Mobile Hero Exact Order (Rule 48-49):
     品牌中心 -> 套餐价格 -> 节点地区 -> 线路知识 -> 使用指南 */
  .courtyard-hero .hero-center {
    order: 1;
    padding: 32px 22px;
    border-bottom: 1px solid var(--border);
  }
  .courtyard-hero .hero-top {
    order: 2;
    padding: 18px 22px;
    border-bottom: 1px solid var(--border);
  }
  .courtyard-hero .hero-left {
    order: 3;
    padding: 20px 22px;
    border-bottom: 1px solid var(--border);
  }
  .courtyard-hero .hero-right {
    order: 4;
    padding: 20px 22px;
    border-bottom: 1px solid var(--border);
  }
  .courtyard-hero .hero-bottom {
    order: 5;
    padding: 18px 22px;
  }

  .hero-top::after,
  .hero-left::after,
  .hero-right::before,
  .hero-bottom::before {
    display: none;
  }

  .courtyard-five-grid,
  .ai-media-courtyard,
  .content-courtyard,
  .faq-courtyard,
  .category-hero,
  .category-featured-grid,
  .article-hero-enclosure {
    display: flex;
    flex-direction: column;
    max-height: none;
  }

  .c-zone-top::after,
  .c-zone-left::after,
  .c-zone-right::before,
  .c-zone-bottom::before,
  .am-zone-top::after,
  .am-zone-left::after,
  .am-zone-right::before,
  .am-zone-bottom::before,
  .cc-top::after,
  .cc-left::after,
  .cc-right::before,
  .cc-bottom::before,
  .fq-top::after,
  .fq-left::after,
  .fq-right::before,
  .fq-bottom-left::before,
  .fq-bottom-right::before,
  .fq-bottom-right::after {
    display: none;
  }

  .c-zone-center,
  .c-zone-top,
  .c-zone-left,
  .c-zone-right,
  .c-zone-bottom,
  .am-zone-center,
  .am-zone-top,
  .am-zone-left,
  .am-zone-right,
  .am-zone-bottom,
  .cc-center,
  .cc-top,
  .cc-left,
  .cc-right,
  .cc-bottom,
  .fq-center,
  .fq-top,
  .fq-left,
  .fq-right,
  .fq-bottom-left,
  .fq-bottom-right {
    padding: 24px 22px;
    border-bottom: 1px solid var(--border);
  }

  /* Mobile Ordering for Enclosures (Rules 72, 94, 128, 166, 172, 233-239) */
  .mobile-order-1 { order: 1; }
  .mobile-order-2 { order: 2; }
  .mobile-order-3 { order: 3; }
  .mobile-order-4 { order: 4; }
  .mobile-order-5 { order: 5; }
  .mobile-order-6 { order: 6; }

  .trouble-sub-split,
  .faq-list-grid-2,
  .related-grid {
    grid-template-columns: 1fr;
    gap: 18px;
  }

  .article-layout {
    grid-template-columns: 1fr;
  }

  .article-sidebar {
    display: none;
  }

  .mobile-toc-box {
    display: block;
  }

  .article-main {
    padding: 28px 22px;
  }

  .category-featured-item + .category-featured-item {
    border-left: none;
    border-top: 1px solid var(--border);
  }

  /* Mobile Footer Order (Rule 240) */
  .footer-top-grid {
    display: flex;
    flex-direction: column;
    gap: 20px;
  }

  .footer-col {
    padding: 0 0 16px 0;
    border-left: none;
    border-bottom: 1px solid var(--border);
  }

  .footer-col:last-child {
    border-bottom: none;
    padding-bottom: 0;
  }

  .footer-bottom-bar {
    flex-direction: column;
    align-items: flex-start;
  }

  .footer-bottom-bar .friend-links {
    order: 1;
  }

  .footer-bottom-bar .copyright-text {
    order: 2;
  }
}

@media (max-width: 640px) {
  body {
    font-size: 16px;
  }

  .container,
  .header-inner {
    padding: 0 18px;
  }

  .hero-brand-title {
    font-size: 38px;
  }

  h1,
  .hero-h1,
  .category-hero-center h1,
  .article-hero-center h1 {
    font-size: 28px;
  }

  h2,
  .section-title {
    font-size: 24px;
  }

  .hero-lead {
    font-size: 18px;
  }

  /* Mobile Table readable block conversion (Rule 274) */
  .minimal-table,
  .minimal-table thead,
  .minimal-table tbody,
  .minimal-table tr,
  .minimal-table td {
    display: block;
    width: 100%;
  }

  .minimal-table thead {
    display: none;
  }

  .minimal-table tr {
    padding: 14px 0;
    border-bottom: 1px solid var(--border);
  }

  .minimal-table tr:last-child {
    border-bottom: none;
  }

  .minimal-table td {
    padding: 6px 0;
    border-bottom: none;
  }

  .minimal-table td::before {
    content: attr(data-label) "：";
    font-weight: 600;
    color: var(--text);
  }
}

/* ==========================================================================
   Reduced Motion Support (Rules 231, 283)
   ========================================================================== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  .btn-header-cta:hover .arrow,
  .btn-primary:hover .arrow,
  .text-link:hover .arrow,
  .boundary-link:hover .arrow {
    transform: none !important;
  }
}