:root {
  --paper: #faf7f0;
  --paper-deep: #f1ecdf;
  --paper-light: #fffaf1;
  --ink: #1c1b18;
  --ink-soft: #625f57;
  --green: #1f5c4d;
  --green-deep: #163f36;
  --green-darkest: #10322b;
  --green-soft: #dce7df;
  --copper: #c9a96a;
  --copper-text: #7d5f2b;
  --line: rgba(28, 27, 24, 0.18);
  --serif: "Songti SC", "STSong", "Noto Serif SC", serif;
  --sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", sans-serif;
  --container: 1120px;
  --article: 720px;
  --gutter: clamp(20px, 4vw, 48px);
  --nav-height: 72px;
  --ease: cubic-bezier(0.22, 1, 0.36, 1);
}

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

html {
  max-width: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-height) + env(safe-area-inset-top) + 24px);
}

body {
  min-width: 320px;
  max-width: 100%;
  margin: 0;
  overflow-x: hidden;
  color: var(--ink);
  background: var(--paper);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.75;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

@supports (overflow: clip) {
  html,
  body {
    overflow-x: clip;
  }
}

a {
  color: inherit;
  text-decoration: none;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
}

p,
h1,
h2,
dd {
  overflow-wrap: anywhere;
}

::selection {
  color: var(--paper);
  background: var(--green);
}

:focus-visible {
  outline: 2px solid var(--green);
  outline-offset: 4px;
}

.case-cta--dark :focus-visible {
  outline-color: #faf7f0;
}

.skip-link {
  position: fixed;
  top: max(8px, env(safe-area-inset-top));
  left: max(8px, env(safe-area-inset-left));
  z-index: 999;
  padding: 9px 13px;
  color: var(--paper);
  background: var(--ink);
  transform: translateY(-160%);
  transition: transform 180ms ease;
}

.skip-link:focus {
  transform: translateY(0);
}

.container {
  width: 100%;
  max-width: calc(var(--container) + (var(--gutter) * 2));
  margin-inline: auto;
  padding-inline: max(var(--gutter), env(safe-area-inset-left)) max(var(--gutter), env(safe-area-inset-right));
}

.wordmark {
  display: inline-flex;
  width: max-content;
  align-items: center;
  gap: 10px;
  font-family: -apple-system, "Helvetica Neue", "PingFang SC", Arial, sans-serif;
  font-size: 21px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
}

.wordmark::before {
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: linear-gradient(120deg, #2e6bff 0%, #13c2c2 100%);
  box-shadow: 0 0 16px #13c2c2;
  content: "";
}

.case-header {
  position: sticky;
  top: 0;
  z-index: 20;
  min-height: calc(var(--nav-height) + env(safe-area-inset-top));
  padding-top: env(safe-area-inset-top);
  border-bottom: 1px solid var(--line);
  background: var(--paper);
}

.case-nav {
  display: flex;
  min-width: 0;
  min-height: var(--nav-height);
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.case-nav-actions {
  display: flex;
  min-width: 0;
  align-items: center;
  gap: clamp(14px, 3vw, 28px);
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 650;
  white-space: nowrap;
  transition: color 180ms ease;
}

.back-link span {
  color: var(--green);
  font-size: 16px;
  line-height: 1;
  transition: transform 200ms var(--ease);
}

.back-link:hover {
  color: var(--green);
}

.back-link:hover span {
  transform: translateX(-3px);
}

.language-placeholder {
  display: inline-grid;
  min-width: 34px;
  min-height: 30px;
  place-items: center;
  border: 1px solid var(--line);
  color: var(--ink-soft);
  font-size: 10px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.12em;
}

.case-hero {
  padding-block: clamp(72px, 10vw, 132px) clamp(64px, 8vw, 104px);
  border-bottom: 1px solid var(--line);
}

.eyebrow {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 0 0 28px;
  color: var(--green);
  font-size: 11px;
  font-weight: 700;
  line-height: 1.4;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.eyebrow::before {
  width: 32px;
  height: 1px;
  flex: 0 0 auto;
  background: currentColor;
  content: "";
}

.case-hero h1 {
  max-width: 920px;
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(40px, 7.2vw, 76px);
  font-weight: 800;
  line-height: 1.08;
  letter-spacing: -0.045em;
  text-wrap: balance;
}

.case-subtitle {
  max-width: 680px;
  margin: 30px 0 0;
  color: var(--ink-soft);
  font-size: clamp(16px, 2vw, 19px);
  line-height: 1.8;
}

.case-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 20px;
  margin-top: 44px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  color: var(--ink-soft);
  font-size: 12px;
}

.meta-label {
  color: var(--green);
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.article-layout {
  display: grid;
  grid-template-columns: minmax(160px, 220px) minmax(0, var(--article));
  justify-content: space-between;
  gap: clamp(48px, 9vw, 112px);
  padding-block: clamp(72px, 9vw, 120px);
}

.article-index {
  align-self: start;
  padding-top: 8px;
}

.index-label {
  display: block;
  margin-bottom: 18px;
  color: var(--green);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.15em;
  text-transform: uppercase;
}

.article-index ol {
  margin: 0;
  padding: 0;
  list-style: none;
  counter-reset: case-index;
}

.article-index li {
  counter-increment: case-index;
  border-top: 1px solid var(--line);
}

.article-index li:last-child {
  border-bottom: 1px solid var(--line);
}

.article-index a {
  display: grid;
  grid-template-columns: 24px minmax(0, 1fr);
  gap: 10px;
  padding: 13px 0;
  color: var(--ink-soft);
  font-size: 12px;
  line-height: 1.55;
  transition: color 180ms ease;
}

.article-index a::before {
  color: var(--copper-text);
  content: counter(case-index, decimal-leading-zero);
  font-variant-numeric: tabular-nums;
}

.article-index a:hover {
  color: var(--green);
}

.article-body {
  min-width: 0;
}

.article-section {
  scroll-margin-top: calc(var(--nav-height) + env(safe-area-inset-top) + 28px);
  padding-bottom: clamp(60px, 8vw, 88px);
}

.article-section + .article-section {
  padding-top: clamp(60px, 8vw, 88px);
  border-top: 1px solid var(--line);
}

.section-number {
  display: block;
  margin-bottom: 16px;
  color: var(--copper-text);
  font-size: 11px;
  font-weight: 700;
  line-height: 1;
  letter-spacing: 0.14em;
}

.article-section h2 {
  margin: 0 0 24px;
  font-family: var(--serif);
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -0.035em;
  text-wrap: balance;
}

.article-section p {
  margin: 0;
  color: var(--ink-soft);
  font-size: 16px;
  line-height: 1.9;
}

.article-section p + p {
  margin-top: 16px;
}

.faq-list {
  margin: 8px 0 0;
}

.faq-item {
  padding: 24px 0;
  border-top: 1px solid var(--line);
}

.faq-item:last-child {
  border-bottom: 1px solid var(--line);
}

.faq-item dt {
  margin: 0 0 8px;
  font-family: var(--serif);
  font-size: 18px;
  font-weight: 800;
  line-height: 1.5;
}

.faq-item dd {
  margin: 0;
  color: var(--ink-soft);
  font-size: 14px;
  line-height: 1.8;
}

.about-strip {
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.about-strip p {
  margin: 0;
  padding-block: 20px;
  font-family: var(--serif);
  font-size: clamp(14px, 1.7vw, 17px);
  font-weight: 700;
  line-height: 1.65;
  text-align: center;
}

.about-strip strong {
  color: var(--green);
  font-weight: 800;
}

.case-footer {
  padding-top: 30px;
  padding-bottom: max(34px, calc(24px + env(safe-area-inset-bottom)));
}

.footer-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.footer-row .wordmark {
  font-size: 18px;
}

.copyright {
  margin: 0;
  color: var(--ink-soft);
  font-size: 12px;
}

.mobile-action-bar {
  display: none;
}

.js.motion .case-hero .container,
.js.motion .article-body > .article-section,
.js.motion .article-body > .case-cta {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 600ms var(--ease), transform 600ms var(--ease);
  will-change: opacity, transform;
}

.js.motion .case-hero .container.is-visible,
.js.motion .article-body > .article-section.is-visible,
.js.motion .article-body > .case-cta.is-visible {
  opacity: 1;
  transform: none;
  will-change: auto;
}

@media (max-width: 768px) {
  :root {
    --gutter: 20px;
    --nav-height: 64px;
    --mobile-action-height: 60px;
  }

  html {
    scroll-padding-top: calc(var(--nav-height) + env(safe-area-inset-top) + 12px);
  }

  body {
    min-height: auto;
    padding-bottom: calc(var(--mobile-action-height) + env(safe-area-inset-bottom));
  }

  .case-nav {
    gap: 12px;
  }

  .case-nav-actions {
    gap: 10px;
  }

  .wordmark {
    font-size: 19px;
  }

  .case-nav a,
  .language-placeholder {
    min-width: 44px;
    min-height: 44px;
  }

  .case-nav .wordmark {
    align-items: center;
  }

  .back-link {
    justify-content: center;
    padding-inline: 4px;
    font-size: 12px;
  }

  .language-placeholder {
    display: none;
  }

  .case-hero {
    min-height: auto;
    padding-block: clamp(48px, 10vw, 64px) clamp(44px, 9vw, 56px);
  }

  .case-hero h1 {
    font-size: clamp(34px, 10.25vw, 44px);
    line-height: 1.1;
    letter-spacing: -0.04em;
  }

  .case-subtitle {
    margin-top: 20px;
    font-size: 16px;
    line-height: 1.7;
  }

  .case-meta {
    margin-top: 28px;
  }

  .article-layout {
    grid-template-columns: minmax(0, 1fr);
    gap: 44px;
    padding-block: clamp(48px, 10vw, 60px) clamp(52px, 11vw, 68px);
  }

  .article-index {
    width: 100%;
    padding-top: 0;
  }

  .article-index ol {
    display: grid;
    grid-template-columns: minmax(0, 1fr);
  }

  .article-index a {
    grid-template-columns: 24px minmax(0, 1fr);
    min-height: 48px;
    align-items: center;
    padding-block: 10px;
  }

  .article-section {
    min-height: auto;
    scroll-margin-top: calc(var(--nav-height) + env(safe-area-inset-top) + 12px);
    padding-bottom: clamp(42px, 8vw, 52px);
  }

  .article-section + .article-section {
    padding-top: clamp(42px, 8vw, 52px);
  }

  .article-section h2 {
    margin-bottom: 20px;
    font-size: clamp(30px, 8.7vw, 36px);
    line-height: 1.17;
  }

  .article-section p,
  body .article-section li {
    font-size: 15px;
    line-height: 1.75;
  }

  .article-section p + p {
    margin-top: 14px;
  }

  body .article-section h3 {
    margin: 28px 0 10px;
    font-size: 20px;
    line-height: 1.35;
  }

  .faq-item {
    min-height: 44px;
    padding-block: 20px;
  }

  .faq-item dt {
    font-size: 17px;
    line-height: 1.45;
  }

  body .case-cta,
  body .case-stats,
  body .method-list,
  body .callout {
    width: 100%;
    max-width: 100%;
  }

  body .case-cta {
    margin-top: 36px;
    padding: 24px 20px;
  }

  body .case-cta a,
  body .cta-link {
    min-height: 48px;
    align-items: center;
    justify-content: center;
  }

  body .method-list {
    margin-top: 18px;
  }

  body .method-list li {
    margin-top: 0;
  }

  body .method-list li + li {
    margin-top: 8px;
  }

  body .method-list--compact li + li {
    margin-top: 0;
  }

  body .case-stats {
    margin-top: 22px;
  }

  body .stat {
    min-width: 0;
    padding: 18px 14px;
  }

  body .callout {
    margin-top: 22px;
    padding: 18px;
  }

  .about-strip p {
    padding-block: 18px;
    font-size: 14px;
  }

  .case-footer {
    padding-top: 24px;
    padding-bottom: 28px;
  }

  .footer-row {
    align-items: flex-start;
  }

  .footer-row a {
    min-width: 44px;
    min-height: 44px;
    align-items: center;
  }

  .mobile-action-bar {
    position: fixed;
    right: 0;
    bottom: 0;
    left: 0;
    z-index: 80;
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr) minmax(118px, 1.3fr);
    min-height: calc(var(--mobile-action-height) + env(safe-area-inset-bottom));
    gap: 4px;
    padding: 5px max(10px, env(safe-area-inset-right)) max(5px, env(safe-area-inset-bottom)) max(10px, env(safe-area-inset-left));
    border-top: 1px solid rgba(28, 27, 24, 0.16);
    background: rgba(250, 247, 240, 0.97);
    box-shadow: 0 -8px 24px rgba(28, 27, 24, 0.06);
    -webkit-backdrop-filter: blur(14px);
    backdrop-filter: blur(14px);
  }

  .mobile-action-link {
    display: flex;
    min-width: 0;
    min-height: 48px;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    gap: 2px;
    border-radius: 7px;
    color: var(--ink-soft);
    font-size: 11px;
    font-weight: 650;
    line-height: 1;
    white-space: nowrap;
  }

  .mobile-action-link svg {
    width: 20px;
    height: 20px;
    fill: none;
    stroke: currentColor;
    stroke-width: 1.6;
    stroke-linecap: round;
    stroke-linejoin: round;
  }

  .mobile-action-link.is-active {
    color: var(--green);
    background: rgba(31, 92, 77, 0.08);
  }

  .mobile-action-link--primary {
    flex-direction: row;
    gap: 7px;
    padding-inline: 12px;
    background: var(--green);
    color: #e8cf98;
    font-weight: 750;
  }

  .mobile-action-link--primary svg {
    width: 19px;
    height: 19px;
  }

  .mobile-action-link--primary:active {
    background: var(--green-deep);
  }
}

@media (max-width: 390px) {
  :root {
    --gutter: 18px;
  }

  .case-nav-actions {
    gap: 8px;
  }

  .case-hero h1 {
    font-size: clamp(33px, 10.2vw, 40px);
  }

  .case-meta {
    display: grid;
    grid-template-columns: 1fr;
    gap: 4px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    transition-delay: 0s !important;
    animation-duration: 0.01ms !important;
    animation-delay: 0s !important;
    animation-iteration-count: 1 !important;
  }

  .js.motion .case-hero .container,
  .js.motion .article-body > .article-section,
  .js.motion .article-body > .case-cta {
    opacity: 1 !important;
    transform: none !important;
  }
}