/* ══════════════════════════════════════════════════════
   style.css · yinguobing.com
   Design: "Ink & Code" — scholarly editorial + technical precision
   ══════════════════════════════════════════════════════ */

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

:root {
  /* Color — ink & paper */
  --paper: #fafaf7;
  --ink: #1a1a18;
  --ink-soft: #4a4a45;
  --ink-dim: #8a8a82;
  --accent: #1e3a5f;
  --accent-glow: #2a5080;
  --rule: #e0ded8;
  --rule-strong: #c8c5bc;
  --surface: #f3f2ed;
  --surface-hover: #ecebe5;

  /* Typography */
  --font-display-zh: 'Noto Serif SC', serif;
  --font-display-latin: 'Lora', Georgia, serif;
  --font-body-zh: 'Noto Sans SC', system-ui, sans-serif;
  --font-body-latin: 'Inter', system-ui, sans-serif;
  --font-display: var(--font-display-zh), var(--font-display-latin);
  --font-body: var(--font-body-zh), var(--font-body-latin);

  /*
   * Type scale — tuned for CJK readability.
   * Chinese glyphs are denser than Latin; they need larger
   * computed px to feel equally readable at the same view distance.
   * 62.5% on html → 1rem = 10px.
   * Minimum CJK readable size is ~15px (anything below is illegible).
   */
  --text-xs: 1.5rem;
  /* 15px — labels, captions (CJK minimum) */
  --text-sm: 1.7rem;
  /* 17px — secondary text */
  --text-base: 1.9rem;
  /* 19px — body */
  --text-lg: 2.1rem;
  /* 21px — lead-ins, large body */
  --text-xl: 2.6rem;
  /* 26px — card headings */
  --text-2xl: 3.4rem;
  /* 34px — sub-headlines */
  --text-3xl: 4.4rem;
  /* 44px — section titles */
  --text-4xl: 6.0rem;
  /* 60px — hero headline */

  /* Spacing */
  --section-py: 12rem;
  --container: 108rem;
  --container-narrow: 72rem;
  --gap: 2.4rem;
  --gap-lg: 4.8rem;
  --gap-xl: 8rem;

  /* Radius */
  --radius-sm: 4px;
  --radius-md: 8px;

  /* Transitions */
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
  --duration: 0.3s;
}

html {
  font-size: 62.5%;
  /* 1rem = 10px */
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: 400;
  line-height: 1.8;
  /* CJK needs more leading than Latin */
  color: var(--ink);
  background: var(--paper);
  overflow-x: hidden;

  /*
   * CJK line-breaking rules:
   * - word-break: break-word — CJK can break at any char boundary,
   *   but Latin words stay whole (unlike break-all).
   * - overflow-wrap — fallback for older engines.
   * - text-wrap: pretty — prevents single-char orphans on last line
   *   and respects CJK punctuation line-start prohibition where supported.
   *   Browsers: Chrome 117+, Safari 17.5+, FF 132+.
   */
  word-break: break-word;
  overflow-wrap: break-word;
  text-wrap: pretty;

  /*
   * Spacing tuned for CJK + Latin mixed text:
   * - letter-spacing: 0.02em — CJK glyphs are full-width (全角) but
   *   at screen sizes they feel dense; a hair of extra space relieves
   *   crowding without breaking the character grid.
   * - word-spacing: 0.05em adds air between CJK and adjacent Latin
   *   words, preventing visual crowding.
   */
  letter-spacing: 0.02em;
  word-spacing: 0.05em;
}

/*
 * CJK body paragraphs — justified for clean block edges.
 * Short text (subtitles, labels, card descriptions) is
 * left-aligned by default and not included here.
 */
.hero-scene,
.hero-target,
.timeline-entry p,
.identity-text p,
.claim-body p,
.case-card-block p,
.costs-bridge p {
  text-align: justify;
  text-justify: inter-ideograph;
  text-align-last: start;
}

/* ── Paper texture overlay ────────────────────────── */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  z-index: 9999;
  pointer-events: none;
  opacity: 0.035;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)'/%3E%3C/svg%3E");
  background-size: 256px 256px;
}

/* ── Container ────────────────────────────────────── */
.container {
  width: min(var(--container), 100% - 4.8rem);
  margin-inline: auto;
}

.container-narrow {
  width: min(var(--container-narrow), 100% - 4.8rem);
  margin-inline: auto;
}

/* ── Navigation ───────────────────────────────────── */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: 2rem 0;
  transition: background var(--duration) var(--ease),
    box-shadow var(--duration) var(--ease);
}

.nav.scrolled {
  background: rgba(250, 250, 247, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 1px 0 var(--rule);
}

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

.nav-logo {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--ink);
  text-decoration: none;
  letter-spacing: 0.02em;
}

.nav-links {
  display: flex;
  gap: 3.2rem;
  list-style: none;
}

.nav-links a {
  font-size: var(--text-sm);
  color: var(--ink-soft);
  text-decoration: none;
  transition: color var(--duration) var(--ease);
  padding-bottom: 4px;
  border-bottom: 1px solid transparent;
}

.nav-links a:hover {
  color: var(--ink);
  border-bottom-color: var(--rule-strong);
}

/* ── Section headings ─────────────────────────────── */
.section-label {
  display: block;
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 500;
  color: var(--ink-dim);
  text-transform: uppercase;
  letter-spacing: 0.12em;
  margin-bottom: 1.6rem;
}

.section-title {
  font-family: var(--font-display);
  font-size: var(--text-3xl);
  font-weight: 600;
  line-height: 1.3;
  letter-spacing: 0.03em;
  color: var(--ink);
  margin-bottom: 2rem;
}

.section-subtitle {
  font-size: var(--text-lg);
  color: var(--ink-soft);
  line-height: 1.7;
}

/* Thin decorative rule */
.rule {
  height: 1px;
  background: var(--rule);
  border: none;
  margin: 0;
}

/*
 * Reveal on scroll.
 *
 * CSS animation (not transition) is used because transitions skip their
 * initial→final change when both states land in the browser's first paint
 * frame — a common issue for above-the-fold elements on page load.
 * animation + animation-delay keeps the element at the keyframe's start
 * state during the delay, so staggered reveals work reliably.
 */
.reveal {
  opacity: 0;
  transform: translateY(2.4rem);
}

.reveal.visible {
  animation: revealIn 0.8s var(--ease) forwards;
}

.reveal-d1.visible {
  animation-delay: 0.05s;
}

.reveal-d2.visible {
  animation-delay: 0.12s;
}

.reveal-d3.visible {
  animation-delay: 0.19s;
}

.reveal-d4.visible {
  animation-delay: 0.26s;
}

@keyframes revealIn {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ════════════════════════════════════════════════════
   HERO
   ════════════════════════════════════════════════════ */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: 16rem 0 8rem;
  position: relative;
  overflow: hidden;
}

/* Hero starfield background (Three.js canvas) */
#hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
}
#hero-bg canvas {
  display: block;
  width: 100% !important;
  height: 100% !important;
}

.hero-content {
  max-width: 72rem;
  position: relative;
  z-index: 1;
}

.hero-eyebrow {
  display: inline-block;
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 500;
  color: var(--accent);
  letter-spacing: 0.15em;
  text-transform: uppercase;
  margin-bottom: 2.4rem;
  padding: 0.6rem 1.4rem;
  border: 1px solid var(--rule-strong);
  border-radius: 2px;
}

.hero-headline {
  font-family: var(--font-display);
  font-size: var(--text-4xl);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: 0.03em;
  color: var(--ink);
  margin-bottom: 2.4rem;
}

.hero-headline mark {
  background: none;
  color: var(--accent);
}

.hero-target {
  font-size: var(--text-lg);
  color: var(--ink-soft);
  line-height: 1.7;
  margin-bottom: 3.2rem;
  padding-left: 2rem;
  border-left: 2px solid var(--rule-strong);
}

.hero-scene {
  font-size: var(--text-base);
  color: var(--ink-dim);
  line-height: 1.8;
  margin-bottom: 5.6rem;
}

.hero-scroll-hint {
  display: inline-flex;
  align-items: center;
  gap: 1.2rem;
  font-size: var(--text-sm);
  color: var(--ink-dim);
  text-decoration: none;
  padding: 1.6rem 0;
  margin-top: 2.4rem;
  transition: color var(--duration) var(--ease);
}

.hero-scroll-hint:hover {
  color: var(--ink-soft);
}

.hero-scroll-arrow {
  display: inline-block;
  animation: arrowPulse 2s ease-in-out infinite;
}

@keyframes arrowPulse {

  0%,
  100% {
    transform: translateX(0);
    opacity: 0.5;
  }

  50% {
    transform: translateX(4px);
    opacity: 1;
  }
}

/* ════════════════════════════════════════════════════
   COSTS
   ════════════════════════════════════════════════════ */
.costs {
  padding: var(--section-py) 0;
  background: var(--surface);
}

.costs-header {
  margin-bottom: var(--gap-xl);
}

.costs-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--gap);
}

.cost-card {
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  padding: 4rem 3.2rem;
  transition: border-color var(--duration) var(--ease),
    box-shadow var(--duration) var(--ease),
    transform var(--duration) var(--ease);
  position: relative;
}

.cost-card:hover {
  border-color: var(--rule-strong);
  box-shadow: 0 2px 16px rgba(0, 0, 0, 0.04);
  transform: translateY(-2px);
}

.cost-card-num {
  font-family: var(--font-display);
  font-size: 5.6rem;
  font-weight: 600;
  color: var(--rule);
  line-height: 1;
  display: block;
  margin-bottom: 2rem;
}

.cost-card h3 {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 600;
  line-height: 1.6;
  color: var(--ink);
  margin-bottom: 1.6rem;
}

.cost-card p {
  font-size: var(--text-sm);
  color: var(--ink-soft);
  line-height: 1.8;
}

.costs-bridge {
  margin-top: var(--gap-xl);
  padding-top: var(--gap-lg);
  border-top: 1px solid var(--rule);
}

.costs-bridge p {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  color: var(--ink-soft);
  font-style: normal;
}

/* ════════════════════════════════════════════════════
   TRUST
   ════════════════════════════════════════════════════ */
.trust {
  padding: var(--section-py) 0;
  background: var(--surface);
}

.trust-header {
  margin-bottom: var(--gap-xl);
}

.trust-motto {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 500;
  color: var(--ink);
  line-height: 1.6;
  padding: 3.2rem 0;
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
  margin-bottom: 6.4rem;
  quotes: "「" "」";
}

.trust-motto::before {
  content: open-quote;
}

.trust-motto::after {
  content: close-quote;
}

.trust-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--gap);
}

.trust-link {
  display: inline-block;
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--accent);
  text-decoration: none;
  margin-top: auto;
  padding-top: 2.4rem;
  align-self: flex-end;
  transition: color var(--duration) var(--ease);
}

.trust-link:hover {
  color: var(--accent-glow);
}

/* ════════════════════════════════════════════════════
   HOW I HELP
   ════════════════════════════════════════════════════ */
.help {
  padding: var(--section-py) 0;
}

.help-header {
  margin-bottom: var(--gap-xl);
}

.help-list {
  display: flex;
  flex-direction: column;
  gap: var(--gap);
}

.help-item {
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  padding: 1.6rem 4rem;
  margin-left: -4rem;
  transition: border-color var(--duration) var(--ease),
    box-shadow var(--duration) var(--ease);
  display: flex;
  flex-direction: column;
  gap: 1.1rem;
}

.help-item:hover {
  border-color: var(--rule-strong);
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.03);
}

.help-q {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--accent);
  line-height: 1.5;
}

.help-a {
  font-size: var(--text-base);
  color: var(--ink-soft);
  line-height: 1.8;
}

/* ════════════════════════════════════════════════════
   CTA
   ════════════════════════════════════════════════════ */
.cta {
  padding: var(--section-py) 0;
  text-align: center;
}

.cta-title {
  font-family: var(--font-display);
  font-size: var(--text-3xl);
  font-weight: 600;
  line-height: 1.3;
  color: var(--ink);
  margin-bottom: 1.6rem;
}

.cta-desc {
  font-size: var(--text-lg);
  color: var(--ink-soft);
  line-height: 1.7;
  max-width: 48rem;
  margin: 0 auto 5.6rem;
}

.cta-actions {
  display: flex;
  justify-content: center;
  gap: var(--gap);
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: 0.6rem;
  padding: 2rem 3.6rem;
  border-radius: var(--radius-md);
  font-family: var(--font-body);
  font-size: var(--text-base);
  font-weight: 500;
  text-decoration: none;
  transition: all var(--duration) var(--ease);
  cursor: pointer;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  border: 1px solid var(--accent);
}

.btn-primary:hover {
  background: var(--accent-glow);
  border-color: var(--accent-glow);
  transform: translateY(-1px);
  box-shadow: 0 4px 20px rgba(30, 58, 95, 0.2);
}

.btn-primary .btn-sub {
  color: rgba(255, 255, 255, 0.65);
}

.btn-secondary {
  background: var(--paper);
  color: var(--ink);
  border: 1px solid var(--rule-strong);
}

.btn-secondary:hover {
  border-color: var(--ink-dim);
  transform: translateY(-1px);
}

.btn-secondary .btn-sub {
  color: var(--ink-soft);
}

.btn-sub {
  font-size: var(--text-xs);
  font-weight: 400;
}

/* WeChat QR hover popup */
.wechat-btn-wrapper {
  position: relative;
  display: inline-flex;
}

.wechat-qr {
  position: absolute;
  bottom: calc(100% + 2rem);
  left: 50%;
  transform: translateX(-50%);
  width: 300px;
  height: auto;
  border-radius: var(--radius-md);
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.15);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s var(--ease);
}

.wechat-qr::after {
  content: '';
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  border: 8px solid transparent;
  border-top-color: var(--paper);
}

.wechat-btn-wrapper:hover .wechat-qr {
  opacity: 1;
}

.cta-footnote {
  margin-top: 4.8rem;
  font-size: var(--text-sm);
  color: var(--ink-dim);
}

/* ════════════════════════════════════════════════════
   FOOTER
   ════════════════════════════════════════════════════ */
.footer {
  padding: 4.8rem 0;
  border-top: 1px solid var(--rule);
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer-brand {
  font-family: var(--font-display);
  font-size: var(--text-sm);
  color: var(--ink-dim);
}

.footer-links {
  display: flex;
  gap: 2.4rem;
  list-style: none;
}

.footer-links a {
  font-size: var(--text-sm);
  color: var(--ink-soft);
  text-decoration: none;
  transition: color var(--duration) var(--ease);
}

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

/* ════════════════════════════════════════════════════
   RESPONSIVE
   ════════════════════════════════════════════════════ */
@media (max-width: 768px) {
  :root {
    --text-4xl: 4.0rem;
    /* 40px — hero on mobile */
    --text-3xl: 3.2rem;
    /* 32px — section titles on mobile */
    --text-2xl: 2.8rem;
    /* 28px — sub-headlines on mobile */
    --section-py: 8rem;
    --gap-xl: 5.6rem;
  }

  .nav-links {
    display: none;
  }

  .hero {
    padding: 12rem 0 6rem;
  }

  .hero-target {
    border-left: none;
    padding-left: 0;
  }

  .costs-grid,
  .trust-grid {
    grid-template-columns: 1fr;
    gap: var(--gap);
  }

  .help-item {
    padding: 2.8rem 2.4rem;
  }

  .help-q::before {
    left: 0;
  }

  .cta-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .btn {
    text-align: center;
  }

  .footer-inner {
    flex-direction: column;
    gap: 1.6rem;
    text-align: center;
  }

  .cost-card-num {
    font-size: 4rem;
  }
}

@media (max-width: 480px) {
  :root {
    --text-4xl: 3.4rem;
    /* 34px — hero on small mobile */
    --text-3xl: 2.8rem;
    /* 28px — section titles on small mobile */
  }

  .container,
  .container-narrow {
    width: 100% - 3.2rem;
  }
}

/* ════════════════════════════════════════════════════
   NAV ACTIVE STATE (shared)
   ════════════════════════════════════════════════════ */
.nav-links .active {
  color: var(--ink);
  border-bottom-color: var(--accent);
}

/* ════════════════════════════════════════════════════
   ABOUT PAGE
   ════════════════════════════════════════════════════ */

/* ── Section header ─────────────────────────────── */
.about-section-head {
  margin-bottom: var(--gap-xl);
}

.about-section-head .section-label {
  margin-bottom: 1.2rem;
}

/* ── Identity (我是谁) ─────────────────────────── */
.about-header {
  padding: 16rem 0 8rem;
}

.identity {
  display: flex;
  gap: 4.8rem;
  align-items: flex-start;
}

.portrait {
  flex-shrink: 0;
  width: 180px;
  height: 180px;
  border-radius: 50%;
  object-fit: cover;
  border: 3px solid var(--rule);
}

.identity-text {
  flex: 1;
  min-width: 0;
}

.identity-name {
  font-family: var(--font-display);
  font-size: var(--text-3xl);
  font-weight: 600;
  line-height: 1.3;
  color: var(--ink);
  margin-bottom: 1.6rem;
}

.identity-text p {
  font-size: var(--text-base);
  color: var(--ink-soft);
  line-height: 1.8;
  margin-bottom: 1.2rem;
}

.identity-motto {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 500;
  line-height: 1.6;
  color: var(--ink);
  border-left: 3px solid var(--accent);
  padding: 0.6rem 0 0.6rem 2.4rem;
  margin-top: 2.4rem;
}

/* ── Timeline (来路) ────────────────────────────── */
.about-timeline {
  padding: var(--section-py) 0;
  background: var(--surface);
}

.timeline {
  position: relative;
  padding-left: 5.6rem;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 0.3rem;
  top: 0.8rem;
  bottom: 0;
  width: 1px;
  background: var(--rule);
}

.timeline-entry {
  position: relative;
  padding-bottom: 4.8rem;
}

.timeline-entry:last-child {
  padding-bottom: 0;
}

.timeline-entry::before {
  content: '';
  position: absolute;
  left: -5.6rem;
  top: 1.5rem;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--accent);
  transform: translateX(-1px);
}

.timeline-entry:last-child::before {
  background: var(--paper);
  border: 2px solid var(--accent);
  box-shadow: 0 0 0 2px var(--paper);
}

.timeline-era {
  font-family: var(--font-body);
  font-size: var(--text-xs);
  font-weight: 500;
  color: var(--ink-dim);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 0.6rem;
}

.timeline-entry h3 {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 600;
  line-height: 1.5;
  color: var(--ink);
  margin-bottom: 1.2rem;
}

.timeline-entry p {
  font-size: var(--text-base);
  color: var(--ink-soft);
  line-height: 1.8;
  max-width: 64rem;
}

/* ── Services (我能做什么) ──────────────────────── */
.about-services {
  padding: var(--section-py) 0;
}

.services-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--gap);
}

.service-card {
  display: flex;
  flex-direction: column;
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  padding: 4rem 3.2rem;
  transition: border-color var(--duration) var(--ease),
    box-shadow var(--duration) var(--ease),
    transform var(--duration) var(--ease);
}

.service-card:hover {
  border-color: var(--rule-strong);
  box-shadow: 0 2px 16px rgba(0, 0, 0, 0.04);
  transform: translateY(-2px);
}

.service-card h3 {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 600;
  line-height: 1.5;
  color: var(--ink);
  margin-bottom: 1.2rem;
  padding-bottom: 1.4rem;
  border-bottom: 2px solid var(--accent);
  display: inline-block;
}

.service-card>p {
  font-size: var(--text-sm);
  color: var(--ink-soft);
  line-height: 1.8;
  margin-bottom: 2rem;
}

.service-done {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 1.4rem;
}

.service-done li {
  font-size: var(--text-sm);
  color: var(--ink-soft);
  line-height: 1.7;
  padding-left: 1.8rem;
  position: relative;
}

.service-done li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 1.2rem;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--rule-strong);
}

/* ── Trust (为什么值得信任) ────────────────────── */
.about-trust {
  padding: var(--section-py) 0;
  background: var(--surface);
}

.trust-stats {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: var(--gap);
  margin-bottom: 6.4rem;
}

.stat-item {
  text-align: center;
  padding: 3.2rem 1.6rem;
}

.stat-num {
  font-family: var(--font-display);
  font-size: var(--text-3xl);
  font-weight: 600;
  line-height: 1.2;
  color: var(--accent);
  white-space: nowrap;
  margin-bottom: 0.8rem;
}

.stat-label {
  font-size: var(--text-xs);
  color: var(--ink-dim);
  line-height: 1.5;
  white-space: nowrap;
}

.trust-closing {
  max-width: 56rem;
  margin: 0 auto;
  text-align: center;
}

.trust-closing p {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 500;
  line-height: 1.6;
  color: var(--ink);
  margin-bottom: 3.2rem;
}

.trust-contact {
  display: flex;
  justify-content: center;
  gap: 2.4rem;
  flex-wrap: wrap;
}

.trust-contact a {
  font-size: var(--text-sm);
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
  transition: color var(--duration) var(--ease);
}

.trust-contact a:hover {
  color: var(--accent-glow);
}

.trust-contact a::after {
  content: ' \2192';
  font-family: var(--font-body-latin);
}

/* ════════════════════════════════════════════════════
   RESPONSIVE — ABOUT
   ════════════════════════════════════════════════════ */
@media (max-width: 768px) {

  /* about */
  .about-header {
    padding: 12rem 0 6rem;
  }

  .identity {
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: 3.2rem;
  }

  .portrait {
    width: 140px;
    height: 140px;
  }

  .identity-name {
    font-size: var(--text-2xl);
  }

  .identity-motto {
    border-left: none;
    border-top: 3px solid var(--accent);
    padding: 2rem 0 0;
    text-align: left;
  }

  .timeline {
    padding-left: 4rem;
  }

  .timeline-entry::before {
    left: -4rem;
    transform: translateX(-1px);
  }

  .timeline-entry h3 {
    font-size: var(--text-lg);
  }

  .services-grid {
    grid-template-columns: 1fr;
    gap: var(--gap);
  }

  .trust-stats {
    grid-template-columns: repeat(2, 1fr);
    gap: var(--gap);
  }

  .stat-num {
    font-size: var(--text-2xl);
  }
}

@media (max-width: 480px) {
  .trust-stats {
    grid-template-columns: 1fr 1fr;
    gap: 1.2rem;
  }

  .stat-item {
    padding: 2rem 0.8rem;
  }
}


/* ════════════════════════════════════════════════════
   CASES PAGE
   ════════════════════════════════════════════════════ */

/* ── Header ──────────────────────────────────── */
.cases-header {
  padding: 16rem 0 8rem;
  text-align: center;
}

.cases-title {
  font-family: var(--font-display);
  font-size: var(--text-3xl);
  font-weight: 600;
  line-height: 1.3;
  color: var(--ink);
  margin-bottom: 2rem;
}

.cases-subtitle {
  font-size: var(--text-lg);
  color: var(--ink-soft);
  line-height: 1.7;
  max-width: 64rem;
  margin: 0 auto;
}

/* ── Claim paragraph (观点) ──────────────────── */
.cases-claim {
  padding: var(--section-py) 0;
  background: var(--surface);
}

.claim-content {
  max-width: 64rem;
}

.claim-title {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 600;
  color: var(--ink);
  margin-bottom: 2.4rem;
}

.claim-quote {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 600;
  line-height: 1.6;
  color: var(--ink);
  border-left: 4px solid var(--ink);
  padding: 1.6rem 0 1.6rem 2.4rem;
  margin-bottom: 3.2rem;
}

.claim-body p {
  font-size: var(--text-base);
  color: var(--ink-soft);
  line-height: 1.8;
  margin-bottom: 1.6rem;
}

/* ── Challenge sections ──────────────────────── */
.cases-challenge {
  padding: var(--section-py) 0;
}

.cases-challenge:nth-child(even of .cases-challenge) {
  background: var(--surface);
}

.challenge-head {
  max-width: 64rem;
  margin-bottom: 4.8rem;
}

.challenge-head .section-subtitle {
  color: var(--ink-soft);
}

/* ── Case card (full) ────────────────────────── */
.case-card {
  display: flex;
  flex-direction: column;
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  padding: 4rem 3.2rem;
  margin-bottom: 3.2rem;
  transition: border-color var(--duration) var(--ease),
    box-shadow var(--duration) var(--ease);
}

.case-card:hover {
  border-color: var(--rule-strong);
  box-shadow: 0 2px 16px rgba(0, 0, 0, 0.04);
}

.case-card-head {
  display: flex;
  align-items: baseline;
  gap: 1.6rem;
  margin-bottom: 2.4rem;
  flex-wrap: wrap;
}

.case-card-head h3 {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 600;
  color: var(--ink);
}

.case-card-tag {
  font-size: var(--text-xs);
  color: var(--ink-dim);
  letter-spacing: 0.04em;
}

.case-card-body {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 2.4rem;
  margin-bottom: 2.4rem;
}

.case-card-block h4 {
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--ink-dim);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 0.8rem;
}

.case-card-block p {
  font-size: var(--text-sm);
  color: var(--ink-soft);
  line-height: 1.8;
  margin-bottom: 1.2rem;
}

.case-card-block ul {
  list-style: none;
  padding: 0;
}

.case-card-block li {
  font-size: var(--text-sm);
  color: var(--ink-soft);
  line-height: 1.7;
  padding-left: 1.6rem;
  position: relative;
  margin-bottom: 0.6rem;
}

.case-card-block li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 1.2rem;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  background: var(--rule-strong);
}

.case-card-conclusion {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--ink);
  line-height: 1.6;
}

.case-card-links {
  margin-top: auto;
  padding-top: 2.4rem;
  align-self: flex-end;
}

.case-link {
  font-size: var(--text-xs);
  color: var(--accent);
  text-decoration: none;
  font-weight: 500;
  transition: color var(--duration) var(--ease);
}

.case-link:hover {
  color: var(--accent-glow);
}

.case-link-sep {
  font-size: var(--text-xs);
  color: var(--ink-dim);
  margin: 0 0.8rem;
}

/* ── Mini card grid (交互问题) ────────────────── */
.cases-mini-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--gap);
}

.mini-card {
  display: flex;
  flex-direction: column;
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  padding: 3.2rem 2.8rem;
  transition: border-color var(--duration) var(--ease),
    box-shadow var(--duration) var(--ease),
    transform var(--duration) var(--ease);
}

.mini-card:hover {
  border-color: var(--rule-strong);
  box-shadow: 0 2px 16px rgba(0, 0, 0, 0.04);
  transform: translateY(-2px);
}

.mini-card-head {
  display: flex;
  align-items: baseline;
  gap: 1.2rem;
  flex-wrap: wrap;
  margin-bottom: 1.6rem;
}

.mini-card-head h3 {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--ink);
}

.mini-card-desc {
  font-size: var(--text-sm);
  color: var(--ink-soft);
  line-height: 1.8;
  margin-bottom: 1.6rem;
}

/* ════════════════════════════════════════════════════
   RESPONSIVE — CASES
   ════════════════════════════════════════════════════ */
@media (max-width: 768px) {
  .cases-header {
    padding: 12rem 0 6rem;
  }

  .cases-title {
    font-size: var(--text-2xl);
  }

  .cases-subtitle {
    font-size: var(--text-base);
  }

  .case-card-body {
    grid-template-columns: 1fr;
    gap: 1.6rem;
  }

  .cases-mini-grid {
    grid-template-columns: 1fr;
    gap: var(--gap);
  }

  .claim-quote {
    font-size: var(--text-lg);
    padding-left: 1.6rem;
  }

}

@media (max-width: 480px) {
  .case-card {
    padding: 2.4rem 1.6rem;
  }

  .mini-card {
    padding: 2.4rem 1.6rem;
  }

  .case-card-head {
    flex-direction: column;
    gap: 0.4rem;
  }
}