:root {
  --bg: #f4f4f1;
  --paper: #ffffff;
  --ink: #101012;
  --ink-2: #3a3a3d;
  --muted: #6c6c70;
  --line: #d8d8d3;
  --dark: #0b0b0f;
  --brand: #2563eb;
  --brand-light: #8eb0ff;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "HarmonyOS Sans SC", "Microsoft YaHei", "Noto Sans SC", Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}
body.menu-open { overflow: hidden; }
a { color: inherit; text-decoration: none; }
img { max-width: 100%; }
button, input, textarea { font: inherit; }
::selection { background: var(--ink); color: var(--bg); }
a:focus-visible, button:focus-visible { outline: 2px solid var(--brand); outline-offset: 4px; }

.shell { width: min(1180px, calc(100% - 40px)); margin: 0 auto; }
.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid rgba(16, 16, 18, .09);
  background: rgba(244, 244, 241, .9);
  backdrop-filter: blur(18px);
}
.nav { min-height: 72px; display: flex; align-items: center; justify-content: space-between; gap: 28px; }
.brand { display: inline-flex; align-items: center; gap: 11px; font-weight: 700; white-space: nowrap; }
.brand-mark { width: 32px; height: 32px; display: grid; place-items: center; border-radius: 9px; color: #fff; background: var(--ink); }
.nav-links { display: flex; align-items: center; gap: 28px; color: var(--ink-2); font-size: 14px; }
.nav-links a:hover, .nav-links a[aria-current="page"] { color: var(--brand); }
.nav-cta { padding: 10px 18px; border-radius: 999px; background: var(--ink); color: #fff !important; }
.nav-cta:hover { background: var(--brand); }
.menu-toggle { display: none; border: 0; background: transparent; padding: 8px; cursor: pointer; }
.menu-toggle span { display: block; width: 23px; height: 2px; margin: 5px 0; background: var(--ink); }

.hero { padding: clamp(82px, 12vw, 150px) 0 clamp(72px, 10vw, 120px); }
.eyebrow { color: var(--brand); font-size: 12px; font-weight: 700; letter-spacing: .12em; text-transform: uppercase; }
.hero h1 { max-width: 920px; margin: 24px 0 28px; font-size: clamp(42px, 7vw, 88px); line-height: 1.04; letter-spacing: -.035em; }
.hero-lead { max-width: 760px; margin: 0; color: var(--ink-2); font-size: clamp(18px, 2vw, 23px); line-height: 1.7; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 36px; }
.button { display: inline-flex; align-items: center; justify-content: center; gap: 8px; min-height: 48px; padding: 0 24px; border: 1px solid var(--ink); border-radius: 999px; font-weight: 650; transition: .2s ease; }
.button.primary { background: var(--ink); color: #fff; }
.button.primary:hover { border-color: var(--brand); background: var(--brand); }
.button.secondary:hover { color: var(--brand); border-color: var(--brand); }

.answer-strip { padding: 34px 0; color: #fff; background: var(--dark); }
.answer-strip p { max-width: 930px; margin: 0; font-size: clamp(17px, 2vw, 22px); line-height: 1.75; }
.answer-strip strong { color: var(--brand-light); }

.section { padding: clamp(72px, 10vw, 120px) 0; }
.section + .section { border-top: 1px solid var(--line); }
.section.dark { color: #fff; background: var(--dark); border: 0; }
.section-head { display: grid; grid-template-columns: minmax(0, 1fr) minmax(280px, 480px); gap: 56px; align-items: end; margin-bottom: 48px; }
.section h2 { margin: 14px 0 0; font-size: clamp(30px, 4.5vw, 54px); line-height: 1.13; letter-spacing: -.025em; }
.section-intro { color: var(--ink-2); font-size: 17px; line-height: 1.75; }
.dark .section-intro { color: #b7b7be; }
.prose { max-width: 820px; }
.prose h2 { margin: 60px 0 18px; font-size: clamp(27px, 3vw, 38px); }
.prose h3 { margin: 36px 0 12px; font-size: 22px; }
.prose p, .prose li { color: var(--ink-2); font-size: 17px; line-height: 1.85; }
.prose li + li { margin-top: 7px; }
.prose .lead { color: var(--ink); font-size: 21px; }
.prose a { color: var(--brand); text-decoration: underline; text-underline-offset: 3px; }
.prose blockquote { margin: 30px 0; padding: 24px 28px; border-left: 4px solid var(--brand); background: #fff; }
.prose blockquote p { margin: 0; color: var(--ink); }

.grid { display: grid; gap: 18px; }
.grid.two { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.card { min-height: 240px; padding: 30px; border: 1px solid var(--line); border-radius: 20px; background: rgba(255,255,255,.45); transition: border-color .2s, transform .2s, background .2s; }
a.card:hover { transform: translateY(-3px); border-color: var(--brand); background: #fff; }
.card .index { color: var(--brand); font-size: 12px; font-weight: 700; letter-spacing: .1em; }
.card h2, .card h3 { margin: 30px 0 12px; font-size: 24px; line-height: 1.25; }
.card p { margin: 0; color: var(--ink-2); line-height: 1.75; }
.card .more { display: inline-block; margin-top: 28px; color: var(--brand); font-weight: 650; }
.dark .card { border-color: rgba(255,255,255,.16); background: rgba(255,255,255,.03); }
.dark .card p { color: #b7b7be; }
.dark a.card:hover { background: rgba(255,255,255,.07); }

.steps { counter-reset: step; display: grid; gap: 0; border-top: 1px solid var(--line); }
.step { counter-increment: step; display: grid; grid-template-columns: 76px minmax(0, 1fr) minmax(260px, 500px); gap: 24px; padding: 30px 0; border-bottom: 1px solid var(--line); align-items: start; }
.step::before { content: "0" counter(step); color: var(--brand); font-weight: 700; }
.step h3 { margin: 0; font-size: 22px; }
.step p { margin: 0; color: var(--ink-2); line-height: 1.7; }

.fact-list { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0 42px; border-top: 1px solid var(--line); }
.fact { padding: 24px 0; border-bottom: 1px solid var(--line); }
.fact dt { color: var(--muted); font-size: 13px; }
.fact dd { margin: 9px 0 0; font-size: 18px; line-height: 1.6; }

.article-list { display: grid; gap: 0; border-top: 1px solid var(--line); }
.article-item { display: grid; grid-template-columns: 150px minmax(0, 1fr) 30px; gap: 26px; padding: 30px 0; border-bottom: 1px solid var(--line); align-items: center; }
.article-item:hover h2 { color: var(--brand); }
.article-meta { color: var(--muted); font-size: 13px; }
.article-item h2 { margin: 0; font-size: clamp(21px, 2.5vw, 30px); transition: color .2s; }
.article-item p { margin: 10px 0 0; color: var(--ink-2); line-height: 1.65; }
.article-arrow { color: var(--brand); font-size: 24px; }

.article-header { padding: clamp(75px, 10vw, 125px) 0 58px; border-bottom: 1px solid var(--line); }
.article-header h1 { max-width: 950px; margin: 22px 0; font-size: clamp(38px, 6vw, 72px); line-height: 1.1; letter-spacing: -.03em; }
.article-dek { max-width: 780px; margin: 0; color: var(--ink-2); font-size: 20px; line-height: 1.75; }
.article-byline { display: flex; flex-wrap: wrap; gap: 16px 30px; margin-top: 28px; color: var(--muted); font-size: 13px; }
.article-body { padding: 58px 0 100px; }
.article-body .prose { margin: 0 auto; }

.faq { display: grid; gap: 0; border-top: 1px solid var(--line); }
.faq details { border-bottom: 1px solid var(--line); }
.faq summary { cursor: pointer; padding: 24px 0; font-size: 18px; font-weight: 650; }
.faq p { max-width: 820px; margin: 0 0 24px; color: var(--ink-2); line-height: 1.75; }

.cta-band { padding: clamp(72px, 10vw, 116px) 0; color: #fff; background: var(--dark); }
.cta-band h2 { max-width: 800px; margin: 0 0 24px; font-size: clamp(34px, 5.5vw, 68px); line-height: 1.1; }
.cta-band p { max-width: 660px; color: #b7b7be; font-size: 18px; line-height: 1.7; }
.cta-band .button { margin-top: 28px; border-color: #fff; color: #fff; }
.cta-band .button:hover { border-color: var(--brand); background: var(--brand); }

.contact-options { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; margin-top: 44px; }
.contact-option { padding: 32px; border: 1px solid var(--line); border-radius: 20px; background: #fff; }
.contact-option small { display: block; color: var(--muted); margin-bottom: 16px; }
.contact-option strong { font-size: clamp(20px, 3vw, 30px); word-break: break-word; }
.contact-option p { color: var(--ink-2); line-height: 1.7; }

.breadcrumb { padding-top: 28px; color: var(--muted); font-size: 13px; }
.breadcrumb a:hover { color: var(--brand); }
.note { padding: 20px 22px; border-radius: 14px; background: #e9efff; color: #244381; line-height: 1.7; }
.tag-row { display: flex; flex-wrap: wrap; gap: 9px; margin-top: 22px; }
.tag { padding: 8px 12px; border: 1px solid var(--line); border-radius: 999px; color: var(--ink-2); font-size: 13px; }

.footer { padding: 38px 0; border-top: 1px solid var(--line); }
.footer-row { display: flex; justify-content: space-between; align-items: center; gap: 20px; color: var(--muted); font-size: 13px; }
.footer-links { display: flex; flex-wrap: wrap; gap: 18px; }
.footer a:hover { color: var(--brand); }

@media (max-width: 900px) {
  .nav-links { display: none; }
  .menu-toggle { display: block; }
  .nav-links.open { position: fixed; inset: 72px 0 0; display: flex; flex-direction: column; align-items: stretch; gap: 0; padding: 24px 20px; background: var(--bg); }
  .nav-links.open a { padding: 18px 8px; border-bottom: 1px solid var(--line); font-size: 20px; }
  .nav-links.open .nav-cta { margin-top: 18px; text-align: center; border: 0; }
  .section-head { grid-template-columns: 1fr; gap: 20px; }
  .grid.three { grid-template-columns: 1fr 1fr; }
  .step { grid-template-columns: 54px 1fr; }
  .step p { grid-column: 2; }
}

@media (max-width: 640px) {
  .shell { width: min(100% - 32px, 1180px); }
  .grid.two, .grid.three, .fact-list, .contact-options { grid-template-columns: 1fr; }
  .card { min-height: 0; }
  .article-item { grid-template-columns: 1fr 24px; }
  .article-meta { grid-column: 1 / -1; }
  .footer-row { align-items: flex-start; flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; }
}