:root {
  --bg: #ffffff;
  --ink: #101012;
  --ink-2: #3f4045;
  --ink-3: #74767d;
  --line: #e6e7ea;
  --panel: #f6f6f7;
  --panel-2: #fbfbfc;
  --accent: #101012;
  --ok: #19724a;
  --warn: #9a6508;
  --radius: 10px;
  --mono: ui-monospace, "SFMono-Regular", "JetBrains Mono", "Cascadia Code", Menlo, Consolas, monospace;
  --sans: -apple-system, BlinkMacSystemFont, "Inter", "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 92px; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

a { color: var(--ink); text-decoration-color: #b9bbc1; text-underline-offset: 3px; }
a:hover { text-decoration-color: var(--ink); }

.wrap { width: min(1120px, calc(100% - 48px)); margin: 0 auto; }

/* top bar */
.topbar {
  position: sticky; top: 0; z-index: 20;
  border-bottom: 1px solid var(--line);
  background: rgba(255, 255, 255, .92);
  backdrop-filter: saturate(180%) blur(10px);
}
.topbar .wrap { display: flex; align-items: center; gap: 22px; min-height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; font-family: var(--mono); font-weight: 700; letter-spacing: .18em; text-decoration: none; }
.brand img { width: 26px; height: auto; display: block; }
.brand span { font-size: 15px; }
.topnav { display: flex; align-items: center; gap: 18px; margin-left: auto; font-size: 13px; }
.topnav a { color: var(--ink-3); text-decoration: none; }
.topnav a:hover { color: var(--ink); }
.topnav .cta {
  border: 1px solid var(--ink); color: var(--ink); padding: 8px 14px;
  font-family: var(--mono); font-size: 12px; letter-spacing: .08em; text-transform: uppercase;
}
.topnav .cta:hover { background: var(--ink); color: #fff; }

/* hero */
.hero { padding: 70px 0 40px; border-bottom: 1px solid var(--line); }
.eyebrow { font-family: var(--mono); font-size: 11.5px; letter-spacing: .22em; text-transform: uppercase; color: var(--ink-3); margin: 0 0 18px; }
.hero h1 { margin: 0; font-size: clamp(30px, 4.6vw, 52px); line-height: 1.12; letter-spacing: -.02em; font-weight: 750; max-width: 880px; }
.hero p.lead { margin: 20px 0 0; max-width: 720px; color: var(--ink-2); font-size: 17px; }
.hero .meta { display: flex; flex-wrap: wrap; gap: 10px 22px; margin-top: 26px; font-family: var(--mono); font-size: 12px; color: var(--ink-3); }
.hero .meta b { color: var(--ink); font-weight: 600; }

/* hub cards */
.section { padding: 54px 0; border-bottom: 1px solid var(--line); }
.section:last-of-type { border-bottom: 0; }
.section-head { display: flex; align-items: baseline; gap: 16px; margin-bottom: 26px; }
.section-head h2 { margin: 0; font-size: 22px; letter-spacing: -.01em; }
.section-head p { margin: 0; color: var(--ink-3); font-size: 13.5px; }
.card-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.card {
  display: flex; flex-direction: column; gap: 10px;
  border: 1px solid var(--line); border-radius: var(--radius);
  padding: 22px 22px 18px; background: var(--panel-2);
  text-decoration: none; color: inherit; min-height: 190px;
  transition: border-color .15s, transform .15s, background .15s;
}
.card:hover { border-color: #b6b8be; background: #fff; transform: translateY(-2px); }
.card .kicker { font-family: var(--mono); font-size: 11px; letter-spacing: .14em; text-transform: uppercase; color: var(--ink-3); }
.card h3 { margin: 0; font-size: 18px; line-height: 1.35; letter-spacing: -.01em; }
.card p { margin: 0; color: var(--ink-2); font-size: 14px; line-height: 1.65; }
.card .more { margin-top: auto; font-family: var(--mono); font-size: 12px; color: var(--ink-3); }
.card:hover .more { color: var(--ink); }
.card.is-muted { opacity: .62; }
.card.is-muted:hover { transform: none; border-color: var(--line); background: var(--panel-2); }

/* layout */
.article-layout { display: grid; grid-template-columns: 230px minmax(0, 1fr); gap: 56px; padding: 48px 0 80px; }
.toc { position: sticky; top: 92px; align-self: start; font-size: 13px; border-left: 1px solid var(--line); padding-left: 18px; }
.toc p { margin: 0 0 12px; font-family: var(--mono); font-size: 11px; letter-spacing: .16em; text-transform: uppercase; color: var(--ink-3); }
.toc a { display: block; padding: 5px 0; color: var(--ink-3); text-decoration: none; line-height: 1.45; }
.toc a:hover, .toc a.is-active { color: var(--ink); }
.toc a.sub { padding-left: 12px; font-size: 12.5px; }

article { min-width: 0; }
article h2 { margin: 52px 0 16px; font-size: 26px; line-height: 1.25; letter-spacing: -.015em; scroll-margin-top: 92px; }
article h2:first-of-type { margin-top: 0; }
article h3 { margin: 30px 0 10px; font-size: 18px; line-height: 1.4; scroll-margin-top: 92px; }
article p { margin: 0 0 16px; color: var(--ink-2); }
article strong { color: var(--ink); }
article ul, article ol { margin: 0 0 18px; padding-left: 24px; color: var(--ink-2); }
article li { margin: 7px 0; }
article code { font-family: var(--mono); font-size: .9em; background: var(--panel); border: 1px solid var(--line); border-radius: 4px; padding: 1px 5px; }
article hr { border: 0; border-top: 1px solid var(--line); margin: 40px 0; }

.lede { font-size: 17px; color: var(--ink-2); margin: 0 0 26px; }
.meta-row { display: flex; flex-wrap: wrap; gap: 8px 20px; margin: 0 0 30px; padding: 14px 16px; background: var(--panel); border: 1px solid var(--line); border-radius: 8px; font-size: 13px; color: var(--ink-2); }
.meta-row b { color: var(--ink); font-weight: 600; }

.steps { counter-reset: step; list-style: none; padding: 0; margin: 20px 0 26px; }
.steps > li {
  counter-increment: step; position: relative;
  padding: 0 0 22px 52px; margin: 0; border-left: 1px solid var(--line); margin-left: 16px;
}
.steps > li:last-child { border-left-color: transparent; padding-bottom: 0; }
.steps > li::before {
  content: counter(step, decimal-leading-zero);
  position: absolute; left: -17px; top: -2px;
  width: 34px; height: 34px; border-radius: 50%;
  display: grid; place-items: center;
  background: var(--ink); color: #fff;
  font-family: var(--mono); font-size: 11px; letter-spacing: .02em;
}
.steps h3 { margin: 0 0 6px; font-size: 17px; }
.steps p { margin: 0 0 8px; }
.steps .see { font-size: 13.5px; color: var(--ink-3); }
.steps .see b { color: var(--ink-2); }

.callout { border-left: 3px solid var(--ink); background: var(--panel); padding: 14px 18px; margin: 20px 0 24px; border-radius: 0 6px 6px 0; }
.callout p:last-child { margin-bottom: 0; }
.callout.warn { border-left-color: #b07a12; background: #fdf8ec; }
.callout.ok { border-left-color: var(--ok); background: #f1f8f4; }
.callout .label { display: block; font-family: var(--mono); font-size: 11px; letter-spacing: .14em; text-transform: uppercase; color: var(--ink-3); margin-bottom: 6px; }

table { width: 100%; border-collapse: collapse; margin: 18px 0 26px; font-size: 14px; }
th, td { text-align: left; padding: 10px 12px; border-bottom: 1px solid var(--line); vertical-align: top; }
th { background: var(--panel); font-size: 12px; font-weight: 650; letter-spacing: .05em; text-transform: uppercase; color: var(--ink-3); border-top: 1px solid var(--line); }
td { color: var(--ink-2); }
td:first-child { color: var(--ink); font-weight: 550; }

figure { margin: 24px 0 30px; }
figure img { display: block; width: auto; max-width: 100%; height: auto; margin: 0 auto; border: 1px solid var(--line); border-radius: 8px; background: var(--panel); }
figure img.shot-narrow { width: min(100%, 260px); }
figcaption { margin-top: 9px; font-size: 12.5px; color: var(--ink-3); line-height: 1.55; }

.faq { list-style: none; padding: 0; margin: 20px 0 0; }
.faq li { border-top: 1px solid var(--line); padding: 18px 0; margin: 0; }
.faq li:last-child { border-bottom: 1px solid var(--line); }
.faq h3 { margin: 0 0 8px; font-size: 16px; }
.faq p { margin: 0; }

.next { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; margin: 26px 0 0; }
.next a { display: block; border: 1px solid var(--line); border-radius: 8px; padding: 16px 18px; text-decoration: none; color: inherit; }
.next a:hover { border-color: #b6b8be; }
.next .kicker { font-family: var(--mono); font-size: 10.5px; letter-spacing: .14em; text-transform: uppercase; color: var(--ink-3); }
.next b { display: block; margin-top: 4px; font-size: 15px; }

.cta-band { margin-top: 48px; border: 1px solid var(--ink); border-radius: var(--radius); padding: 28px 30px; display: flex; align-items: center; gap: 20px; justify-content: space-between; background: #fff; }
.cta-band h2 { margin: 0 0 6px; font-size: 20px; }
.cta-band p { margin: 0; font-size: 14px; color: var(--ink-2); }
.btn { display: inline-block; border: 1px solid var(--ink); background: var(--ink); color: #fff; padding: 12px 20px; text-decoration: none; font-family: var(--mono); font-size: 12px; letter-spacing: .08em; text-transform: uppercase; white-space: nowrap; border-radius: 4px; }
.btn:hover { background: #fff; color: var(--ink); }
.btn.ghost { background: #fff; color: var(--ink); }
.btn.ghost:hover { background: var(--ink); color: #fff; }

.footer { border-top: 1px solid var(--line); padding: 40px 0 56px; margin-top: 20px; }
.footer .wrap { display: flex; flex-wrap: wrap; gap: 20px; align-items: center; justify-content: space-between; font-size: 13px; color: var(--ink-3); }
.footer a { color: var(--ink-2); text-decoration: none; margin-right: 18px; }
.footer a:hover { color: var(--ink); }

.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

@media (max-width: 980px) {
  .card-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .article-layout { grid-template-columns: 1fr; gap: 30px; }
  .toc { position: static; border-left: 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); padding: 18px 0; display: flex; flex-wrap: wrap; gap: 4px 18px; }
  .toc p { width: 100%; margin-bottom: 4px; }
  .toc a { padding: 2px 0; }
  .toc a.sub { display: none; }
}

@media (max-width: 720px) {
  body { font-size: 15.5px; }
  .wrap { width: calc(100% - 32px); }
  .topnav a:not(.cta) { display: none; }
  .hero { padding: 46px 0 32px; }
  .card-grid { grid-template-columns: 1fr; }
  .section { padding: 40px 0; }
  .article-layout { padding: 32px 0 56px; }
  article h2 { font-size: 23px; margin-top: 42px; }
  .cta-band { flex-direction: column; align-items: flex-start; }
  .next { grid-template-columns: 1fr; }
  th, td { padding: 9px 8px; }
  table { font-size: 13px; }
}