/* ===================================================
   克拉云 KELAYUN - LINEAR PRODUCT NARRATIVE
   Theme: Linear Product Narrative System
   Version: 3.0.0
   =================================================== */

:root {
  /* 调色板 Palette */
  --bg-main: #FAFAF8;
  --bg-white: #FFFFFF;
  --bg-soft-gray: #F0F2EF;
  --bg-device: #F3F5F2;
  --bg-media: #F4F6FA;
  --bg-blog: #F6F6F3;
  --bg-footer: #F0F2EF;

  --text-primary: #182028;
  --text-body: #48515A;
  --text-secondary: #7C848B;
  --text-muted: #9BA3A9;

  --color-brand: #3972FF;
  --color-brand-hover: #265CE0;
  --color-sage: #84A98C;
  --color-sage-soft: #EFF5F0;
  --color-blue-soft: #EEF3FF;

  --border-light: #E2E5E1;
  --border-subtle: #ECEFEA;

  --font-sans: -apple-system, BlinkMacSystemFont, "SF Pro Display", "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;

  --radius-btn: 10px;
  --radius-sm: 6px;
  --radius-md: 8px;

  --max-width: 1160px;
  --header-height: 68px;
}

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

html {
  font-family: var(--font-sans);
  background-color: var(--bg-main);
  color: var(--text-body);
  font-size: 16px;
  line-height: 1.68;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--bg-main);
  color: var(--text-body);
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
  transition: color 0.2s ease, opacity 0.2s ease;
}

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

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

ul, ol {
  list-style: none;
}

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

/* Accessibility */
:focus-visible {
  outline: 2px solid var(--color-brand);
  outline-offset: 3px;
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

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

.container-narrow {
  width: 100%;
  max-width: 860px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Buttons */
.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  background-color: var(--color-brand);
  color: #FFFFFF !important;
  font-size: 15px;
  font-weight: 500;
  border-radius: var(--radius-btn);
  transition: background-color 0.2s ease, transform 0.15s ease;
}

.btn-primary:hover {
  background-color: var(--color-brand-hover);
  color: #FFFFFF;
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 22px;
  background-color: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-light);
  font-size: 15px;
  font-weight: 500;
  border-radius: var(--radius-btn);
  transition: border-color 0.2s ease, color 0.2s ease, background-color 0.2s ease;
}

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

.btn-text {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--text-secondary);
  font-size: 15px;
  font-weight: 500;
  padding: 6px 0;
  transition: color 0.2s ease;
}

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

/* ===================================================
   Header (Minimal Product Header)
   =================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background-color: rgba(250, 250, 248, 0.94);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-light);
  transition: background-color 0.3s ease, border-color 0.3s ease;
}

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

.header-brand {
  display: flex;
  align-items: baseline;
  gap: 8px;
}

.brand-name {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: -0.02em;
}

.brand-tag {
  font-size: 11px;
  font-weight: 600;
  color: var(--text-secondary);
  letter-spacing: 0.12em;
  font-family: var(--font-mono);
}

.header-nav {
  display: flex;
  align-items: center;
  gap: 32px;
}

.nav-link {
  font-size: 14px;
  font-weight: 500;
  color: var(--text-body);
  position: relative;
  padding: 4px 0;
}

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

.nav-link.active::after {
  content: "";
  position: absolute;
  bottom: -2px;
  left: 0;
  right: 0;
  height: 2px;
  background-color: var(--color-brand);
}

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

.header-actions .btn-primary {
  padding: 8px 18px;
  font-size: 14px;
}

/* Mobile Menu Toggle */
.mobile-menu-btn {
  display: none;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.1em;
  padding: 8px 14px;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  background: var(--bg-white);
}

.mobile-nav-drawer {
  display: none;
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  bottom: 0;
  background-color: var(--bg-white);
  border-top: 1px solid var(--border-light);
  padding: 24px 28px;
  overflow-y: auto;
  z-index: 99;
}

.mobile-nav-drawer.is-open {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.mobile-nav-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.mobile-nav-link {
  font-size: 17px;
  font-weight: 500;
  color: var(--text-primary);
  padding: 10px 0;
  border-bottom: 1px solid var(--border-subtle);
}

.mobile-nav-cta {
  margin-top: 16px;
  width: 100%;
}

/* ===================================================
   Hero (Quiet Product Hero)
   =================================================== */
.hero-section {
  background-color: var(--bg-main);
  padding: 72px 0 54px 0;
  border-bottom: 1px solid var(--border-light);
  min-height: 620px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.hero-content {
  max-width: 960px;
  margin: 0 auto;
  width: 100%;
}

.hero-meta {
  display: inline-block;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--color-brand);
  text-transform: uppercase;
  margin-bottom: 24px;
  font-family: var(--font-mono);
}

.hero-title-group {
  margin-bottom: 24px;
}

.hero-h1 {
  font-size: 48px;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 14px;
}

.hero-h1 .brand-lead {
  display: block;
  font-size: 56px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
  letter-spacing: -0.03em;
}

.hero-h1 .narrative-lead {
  display: block;
  font-size: 48px;
  font-weight: 600;
  color: var(--text-body);
}

.hero-subhead {
  font-size: 26px;
  font-weight: 400;
  color: var(--text-secondary);
  line-height: 1.4;
  margin-bottom: 24px;
  letter-spacing: -0.01em;
}

.hero-intro {
  font-size: 17px;
  color: var(--text-body);
  line-height: 1.75;
  max-width: 820px;
  margin-bottom: 36px;
}

.hero-actions {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 20px;
  margin-bottom: 48px;
}

/* Chapter Index at Hero Bottom */
.hero-chapters-index {
  padding-top: 28px;
  border-top: 1px solid var(--border-light);
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 32px;
}

.chapter-anchor-link {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.12em;
  color: var(--text-secondary);
  font-family: var(--font-mono);
  transition: color 0.2s ease;
}

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

/* ===================================================
   Chapter Header Component
   =================================================== */
.chapter-meta-line {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-light);
}

.chapter-num {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.16em;
  color: var(--text-secondary);
  font-family: var(--font-mono);
  text-transform: uppercase;
}

.chapter-label {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--color-brand);
  font-family: var(--font-mono);
}

.chapter-h2 {
  font-size: 34px;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.25;
  letter-spacing: -0.02em;
  margin-bottom: 40px;
}

/* ===================================================
   Chapter 01: GLOBAL (Editorial Flow)
   =================================================== */
.section-global {
  background-color: var(--bg-white);
  padding: 88px 0;
  border-bottom: 1px solid var(--border-light);
}

.global-masthead {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  margin-bottom: 48px;
}

.global-watermark {
  font-size: clamp(48px, 9vw, 96px);
  font-weight: 800;
  color: #ECEFEA;
  line-height: 0.9;
  letter-spacing: -0.04em;
  font-family: var(--font-sans);
  text-transform: uppercase;
  user-select: none;
}

.global-regions-count {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.14em;
  color: var(--text-secondary);
  font-family: var(--font-mono);
  padding-bottom: 8px;
}

.global-editorial-flow {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.region-flow-row {
  display: grid;
  grid-template-columns: 240px 1fr;
  align-items: baseline;
  padding: 28px 0;
  border-top: 1px solid var(--border-light);
}

.region-flow-row:last-child {
  border-bottom: 1px solid var(--border-light);
}

.region-flow-header {
  display: flex;
  align-items: baseline;
  gap: 12px;
}

.region-flow-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  font-family: var(--font-mono);
}

.region-count-badge {
  font-size: 12px;
  font-weight: 600;
  color: var(--color-brand);
  font-family: var(--font-mono);
}

.region-nodes-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 18px;
}

.region-node-item {
  font-size: 16px;
  color: var(--text-body);
  display: flex;
  align-items: center;
}

.region-node-item:not(:last-child)::after {
  content: "/";
  margin-left: 18px;
  color: var(--border-light);
}

.global-subtext {
  margin-top: 36px;
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ===================================================
   Chapter 02: DEVICE (Device Sequence)
   =================================================== */
.section-device {
  background-color: var(--bg-device);
  padding: 88px 0;
  border-bottom: 1px solid var(--border-light);
}

.device-sequence-track {
  position: relative;
  margin-top: 32px;
  padding-left: 36px;
}

.device-sequence-line {
  position: absolute;
  top: 16px;
  bottom: 24px;
  left: 7px;
  width: 2px;
  background-color: var(--border-light);
}

.device-seq-item {
  position: relative;
  display: grid;
  grid-template-columns: 80px 180px 1fr;
  align-items: baseline;
  padding: 24px 0;
  border-bottom: 1px solid rgba(226, 229, 225, 0.7);
}

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

.device-dot {
  position: absolute;
  left: -33px;
  top: 30px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background-color: var(--bg-white);
  border: 2px solid var(--color-brand);
}

.device-num {
  font-size: 13px;
  font-weight: 600;
  color: var(--color-brand);
  font-family: var(--font-mono);
}

.device-name-group {
  display: flex;
  flex-direction: column;
}

.device-name {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
}

.device-platform {
  font-size: 12px;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-family: var(--font-mono);
}

.device-desc {
  font-size: 15px;
  color: var(--text-body);
  line-height: 1.6;
}

/* ===================================================
   Chapter 03: AI (Dedicated Typography Chapter)
   =================================================== */
.section-ai {
  background-color: var(--bg-white);
  padding: 88px 0;
  border-bottom: 1px solid var(--border-light);
}

.ai-typography-wrapper {
  margin-top: 32px;
  padding: 40px 0;
  border-top: 1px solid var(--border-light);
  border-bottom: 1px solid var(--border-light);
}

.ai-tools-list {
  display: flex;
  flex-wrap: wrap;
  gap: 20px 48px;
  align-items: baseline;
}

.ai-tool-item {
  font-size: clamp(26px, 3.8vw, 44px);
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: -0.02em;
  transition: color 0.2s ease;
}

.ai-tool-item:hover {
  color: var(--color-brand);
}

.ai-scenario-block {
  margin-top: 36px;
  max-width: 760px;
  font-size: 16px;
  color: var(--text-body);
  line-height: 1.8;
}

.ai-scenario-block p:not(:last-child) {
  margin-bottom: 12px;
}

/* ===================================================
   Chapter 04: MEDIA (Horizontal Media Strip)
   =================================================== */
.section-media {
  background-color: var(--bg-media);
  padding: 88px 0;
  border-bottom: 1px solid var(--border-light);
}

.media-strip-header {
  margin-top: 24px;
  padding: 32px 0;
  border-top: 1px solid var(--border-light);
  border-bottom: 1px solid var(--border-light);
}

.media-strip-names {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.media-name {
  font-size: clamp(20px, 3vw, 32px);
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.media-details-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 36px;
  margin-top: 48px;
}

.media-detail-col h3 {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.media-detail-col p {
  font-size: 14px;
  color: var(--text-body);
  line-height: 1.7;
}

.media-guide-action {
  margin-top: 40px;
  padding-top: 24px;
  border-top: 1px solid var(--border-light);
}

/* ===================================================
   Chapter 05: PLANS (Plan Ladder)
   =================================================== */
.section-plans {
  background-color: var(--bg-white);
  padding: 88px 0;
  border-bottom: 1px solid var(--border-light);
}

.plan-ladder-container {
  display: flex;
  flex-direction: column;
  gap: 20px;
  margin-top: 32px;
}

.plan-ladder-row {
  display: grid;
  grid-template-columns: 80px 1fr 240px;
  align-items: center;
  padding: 28px 32px;
  background-color: var(--bg-main);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  transition: border-color 0.2s ease, transform 0.15s ease;
}

.plan-ladder-row:hover {
  border-color: #CBD0C8;
}

.plan-ladder-row.is-recommended {
  border-color: var(--color-brand);
  background-color: var(--bg-white);
}

.plan-ladder-num {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-secondary);
  font-family: var(--font-mono);
}

.plan-ladder-main {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.plan-title-line {
  display: flex;
  align-items: center;
  gap: 12px;
}

.plan-title {
  font-size: 20px;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.01em;
}

.plan-zh-name {
  font-size: 14px;
  color: var(--text-secondary);
}

.plan-badge-recommended {
  display: inline-block;
  padding: 2px 8px;
  background-color: var(--color-blue-soft);
  color: var(--color-brand);
  font-size: 11px;
  font-weight: 600;
  border-radius: 4px;
  letter-spacing: 0.08em;
  font-family: var(--font-mono);
}

.plan-data-volume {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  font-family: var(--font-mono);
}

.plan-features-list {
  font-size: 13px;
  color: var(--text-secondary);
}

.plan-ladder-action {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 10px;
}

.plan-price-block {
  text-align: right;
}

.plan-price {
  font-size: 24px;
  font-weight: 700;
  color: var(--text-primary);
  font-family: var(--font-sans);
}

.plan-period {
  font-size: 13px;
  color: var(--text-secondary);
}

.plan-ladder-action .btn-primary,
.plan-ladder-action .btn-secondary {
  padding: 9px 20px;
  font-size: 14px;
}

/* ===================================================
   Chapter 06: GUIDES (3 Guide Chapters 3×3)
   =================================================== */
.section-guides {
  background-color: var(--bg-blog);
  padding: 88px 0;
  border-bottom: 1px solid var(--border-light);
}

.guide-groups-container {
  display: flex;
  flex-direction: column;
  gap: 56px;
  margin-top: 32px;
}

.guide-group-block {
  display: grid;
  grid-template-columns: 240px 1fr;
  gap: 40px;
  padding-top: 28px;
  border-top: 1px solid var(--border-light);
}

.guide-group-sidebar {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.guide-group-num {
  font-size: 13px;
  font-weight: 600;
  color: var(--color-brand);
  font-family: var(--font-mono);
}

.guide-group-title {
  font-size: 20px;
  font-weight: 600;
  color: var(--text-primary);
}

.guide-articles-list {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.article-row-item {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding-bottom: 20px;
  border-bottom: 1px solid rgba(226, 229, 225, 0.7);
}

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

.article-row-meta {
  display: flex;
  align-items: center;
  gap: 14px;
  font-size: 12px;
  color: var(--text-secondary);
  font-family: var(--font-mono);
}

.article-row-category {
  color: var(--color-brand);
  font-weight: 600;
}

.article-row-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.4;
}

.article-row-title a:hover {
  color: var(--color-brand);
}

.article-row-summary {
  font-size: 14px;
  color: var(--text-body);
  line-height: 1.6;
}

/* ===================================================
   Chapter 07: FAQ (Centered Question Flow)
   =================================================== */
.section-faq {
  background-color: var(--bg-white);
  padding: 88px 0;
  border-bottom: 1px solid var(--border-light);
}

.faq-flow-wrapper {
  margin-top: 36px;
  display: flex;
  flex-direction: column;
}

.faq-flow-item {
  border-bottom: 1px solid var(--border-light);
}

.faq-flow-question {
  width: 100%;
  text-align: left;
  padding: 22px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  font-size: 17px;
  font-weight: 600;
  color: var(--text-primary);
  background: none;
  border: none;
  cursor: pointer;
  transition: color 0.2s ease;
}

.faq-flow-question:hover {
  color: var(--color-brand);
}

.faq-q-left {
  display: flex;
  align-items: baseline;
  gap: 16px;
}

.faq-index {
  font-size: 12px;
  font-weight: 600;
  color: var(--color-brand);
  font-family: var(--font-mono);
}

.faq-toggle-icon {
  font-size: 18px;
  color: var(--text-secondary);
  transition: transform 0.25s ease;
  flex-shrink: 0;
}

.faq-flow-item.is-open .faq-toggle-icon {
  transform: rotate(45deg);
  color: var(--color-brand);
}

.faq-flow-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease, padding 0.3s ease;
}

.faq-flow-item.is-open .faq-flow-answer {
  max-height: 500px;
  padding-bottom: 24px;
}

.faq-flow-answer p {
  font-size: 15px;
  color: var(--text-body);
  line-height: 1.75;
  padding-left: 32px;
}

/* ===================================================
   Footer (Soft Product Closing)
   =================================================== */
.site-footer {
  background-color: var(--bg-footer);
  padding: 64px 0 40px 0;
  border-top: 1px solid var(--border-light);
  font-size: 14px;
}

.footer-top-row {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  padding-bottom: 40px;
  border-bottom: 1px solid var(--border-light);
}

.footer-brand-title {
  font-size: 20px;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.01em;
  margin-bottom: 6px;
}

.footer-brand-tagline {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.5;
}

.footer-links-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr) 1.5fr;
  gap: 40px;
  padding: 44px 0 36px 0;
  border-bottom: 1px solid var(--border-light);
}

.footer-col-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-primary);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 18px;
  font-family: var(--font-mono);
}

.footer-links-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.footer-links-list a {
  color: var(--text-body);
  transition: color 0.2s ease;
}

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

.footer-external-links {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.footer-bottom-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 28px;
  font-size: 13px;
  color: var(--text-secondary);
}

.footer-bottom-nav {
  display: flex;
  gap: 20px;
}

/* ===================================================
   Article & Category Page Styles (Product Document)
   =================================================== */
.page-container {
  padding: 48px 0 88px 0;
}

.breadcrumb-nav {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

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

.breadcrumb-separator {
  color: var(--text-muted);
}

.article-header {
  margin-bottom: 36px;
  padding-bottom: 28px;
  border-bottom: 1px solid var(--border-light);
}

.article-category-badge {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.12em;
  color: var(--color-brand);
  text-transform: uppercase;
  margin-bottom: 14px;
  font-family: var(--font-mono);
}

.article-h1 {
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 700;
  color: var(--text-primary);
  line-height: 1.25;
  letter-spacing: -0.02em;
  margin-bottom: 18px;
}

.article-lead {
  font-size: 18px;
  color: var(--text-body);
  line-height: 1.68;
  margin-bottom: 22px;
}

.article-meta-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 18px;
  font-size: 13px;
  color: var(--text-secondary);
  font-family: var(--font-mono);
}

/* Quick Answer Box (GEO Direct Answer) */
.quick-answer {
  background-color: var(--color-blue-soft);
  border: 1px solid #D7E3FF;
  border-left: 4px solid var(--color-brand);
  border-radius: var(--radius-sm);
  padding: 22px 26px;
  margin: 32px 0 40px 0;
}

.quick-answer h2 {
  font-size: 16px;
  font-weight: 700;
  color: var(--color-brand);
  margin-bottom: 10px;
  letter-spacing: 0.02em;
}

.quick-answer p {
  font-size: 15px;
  color: var(--text-primary);
  line-height: 1.7;
}

/* Article Table of Contents */
.article-toc {
  background-color: var(--bg-soft-gray);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  padding: 20px 24px;
  margin-bottom: 40px;
}

.article-toc h3 {
  font-size: 15px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.article-toc ol {
  list-style: decimal;
  padding-left: 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.article-toc a {
  font-size: 14px;
  color: var(--text-body);
}

.article-toc a:hover {
  color: var(--color-brand);
  text-decoration: underline;
}

/* Article Body Content */
.article-content {
  font-size: 16px;
  line-height: 1.8;
  color: var(--text-body);
}

.article-content h2 {
  font-size: 24px;
  font-weight: 700;
  color: var(--text-primary);
  margin: 44px 0 18px 0;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--border-light);
}

.article-content h3 {
  font-size: 19px;
  font-weight: 600;
  color: var(--text-primary);
  margin: 30px 0 12px 0;
}

.article-content p {
  margin-bottom: 20px;
}

.article-content ol,
.article-content ul {
  margin: 16px 0 24px 24px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.article-content ol {
  list-style: decimal;
}

.article-content ul {
  list-style: disc;
}

.article-content li {
  line-height: 1.7;
}

.article-content table {
  width: 100%;
  border-collapse: collapse;
  margin: 28px 0;
  font-size: 14px;
  border: 1px solid var(--border-light);
  background: var(--bg-white);
}

.article-content th,
.article-content td {
  padding: 12px 16px;
  border: 1px solid var(--border-light);
  text-align: left;
}

.article-content th {
  background-color: var(--bg-soft-gray);
  font-weight: 600;
  color: var(--text-primary);
}

.article-content figure {
  margin: 32px 0;
}

.article-content figure img {
  width: 100%;
  height: auto;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-light);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.03);
}

.article-content figcaption {
  font-size: 13px;
  color: var(--text-secondary);
  text-align: center;
  margin-top: 10px;
}

/* Article In-text CTA */
.article-inline-cta {
  background-color: var(--color-sage-soft);
  border: 1px solid #D6E4DA;
  border-radius: var(--radius-md);
  padding: 24px 28px;
  margin: 40px 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.inline-cta-text h4 {
  font-size: 17px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.inline-cta-text p {
  font-size: 14px;
  color: var(--text-body);
  margin: 0;
}

/* Related Articles */
.related-articles-section {
  margin-top: 64px;
  padding-top: 36px;
  border-top: 1px solid var(--border-light);
}

.related-articles-section h3 {
  font-size: 20px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 24px;
}

.related-articles-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.related-article-card {
  padding: 20px;
  background-color: var(--bg-white);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  display: flex;
  flex-direction: column;
  gap: 8px;
  transition: border-color 0.2s ease;
}

.related-article-card:hover {
  border-color: var(--color-brand);
}

.related-card-category {
  font-size: 11px;
  font-weight: 600;
  color: var(--color-brand);
  font-family: var(--font-mono);
  text-transform: uppercase;
}

.related-card-title {
  font-size: 15px;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.45;
}

/* Category Page (Linear Content Flow) */
.category-header {
  margin-bottom: 44px;
  padding-bottom: 28px;
  border-bottom: 1px solid var(--border-light);
}

.category-flow-list {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.category-article-item {
  padding-bottom: 32px;
  border-bottom: 1px solid var(--border-light);
}

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

.category-article-title {
  font-size: 22px;
  font-weight: 600;
  color: var(--text-primary);
  margin: 8px 0 12px 0;
}

.category-article-title a:hover {
  color: var(--color-brand);
}

/* ===================================================
   Responsive Breakpoints
   1440, 1024, 768, 430, 390, 375
   =================================================== */
@media (max-width: 1024px) {
  .media-details-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }
  .footer-links-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
  }
  .plan-ladder-row {
    grid-template-columns: 60px 1fr 200px;
    padding: 24px 20px;
  }
}

@media (max-width: 860px) {
  .header-nav {
    display: none;
  }
  .mobile-menu-btn {
    display: block;
  }
  .region-flow-row {
    grid-template-columns: 1fr;
    gap: 12px;
  }
  .device-seq-item {
    grid-template-columns: 60px 1fr;
    gap: 8px;
  }
  .device-desc {
    grid-column: 2 / 3;
  }
  .guide-group-block {
    grid-template-columns: 1fr;
    gap: 20px;
  }
  .plan-ladder-row {
    grid-template-columns: 1fr;
    gap: 16px;
  }
  .plan-ladder-action {
    align-items: flex-start;
    flex-direction: row;
    justify-content: space-between;
    width: 100%;
    padding-top: 14px;
    border-top: 1px solid var(--border-light);
  }
  .plan-price-block {
    text-align: left;
  }
  .related-articles-grid {
    grid-template-columns: 1fr;
  }
  .hero-h1 {
    font-size: 38px;
  }
  .hero-h1 .brand-lead {
    font-size: 42px;
  }
  .hero-h1 .narrative-lead {
    font-size: 36px;
  }
  .hero-subhead {
    font-size: 22px;
  }
  .chapter-h2 {
    font-size: 28px;
  }
  .footer-top-row {
    flex-direction: column;
    gap: 20px;
  }
  .footer-bottom-bar {
    flex-direction: column;
    gap: 16px;
    align-items: flex-start;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 20px;
  }
  .hero-h1 {
    font-size: 32px;
  }
  .hero-h1 .brand-lead {
    font-size: 36px;
  }
  .hero-h1 .narrative-lead {
    font-size: 30px;
  }
  .hero-subhead {
    font-size: 19px;
  }
  .hero-intro {
    font-size: 15px;
  }
  .chapter-h2 {
    font-size: 24px;
  }
  .hero-actions {
    flex-direction: column;
    align-items: stretch;
  }
  .hero-actions .btn-primary,
  .hero-actions .btn-secondary {
    width: 100%;
  }
  .hero-chapters-index {
    gap: 16px;
  }
  .device-seq-item {
    grid-template-columns: 44px 1fr;
  }
  .device-dot {
    left: -31px;
  }
  .footer-links-grid {
    grid-template-columns: 1fr;
  }
  .article-inline-cta {
    flex-direction: column;
    align-items: stretch;
  }
}