:root {
  color-scheme: light dark;
  --bg: #f2f5f3;
  --surface: #fbfcfb;
  --surface-2: #e8eeeb;
  --text: #17201d;
  --muted: #56635e;
  --line: #cfd8d3;
  --accent: #245c4a;
  --accent-strong: #174536;
  --accent-soft: #d8e7e0;
  --danger: #8b3a35;
  --shadow: 0 18px 50px rgba(25, 54, 44, 0.10);
  --radius: 16px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #111714;
    --surface: #18201c;
    --surface-2: #222d28;
    --text: #eef3f0;
    --muted: #abb8b2;
    --line: #34423b;
    --accent: #76b59d;
    --accent-strong: #9acbb8;
    --accent-soft: #243f35;
    --danger: #dc8b83;
    --shadow: 0 18px 50px rgba(0, 0, 0, 0.28);
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 17px;
  line-height: 1.75;
  text-rendering: optimizeLegibility;
}
a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--accent-strong); }
img { display: block; max-width: 100%; }

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: blur(18px);
}
.nav {
  width: min(1180px, calc(100% - 40px));
  min-height: 68px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
}
.brand { color: var(--text); font-weight: 760; text-decoration: none; letter-spacing: -0.02em; }
.nav-links { display: flex; gap: 22px; align-items: center; white-space: nowrap; font-size: 14px; }
.nav-links a { color: var(--muted); text-decoration: none; }
.nav-links a[aria-current="page"], .nav-links a:hover { color: var(--text); }

.page { width: min(1180px, calc(100% - 40px)); margin: 0 auto; padding: 64px 0 96px; }
.hero {
  min-height: min(780px, calc(100dvh - 68px));
  display: grid;
  grid-template-columns: 1.06fr 0.94fr;
  gap: 48px;
  align-items: center;
}
.hero.compact { min-height: auto; padding: 34px 0 54px; }
.kicker { color: var(--accent); font-size: 14px; font-weight: 760; letter-spacing: 0.08em; text-transform: uppercase; }
h1, h2, h3 { margin: 0; letter-spacing: -0.035em; line-height: 1.14; }
h1 { max-width: 13ch; margin-top: 16px; font-size: clamp(42px, 6vw, 72px); }
h2 { margin-top: 72px; font-size: clamp(30px, 4vw, 46px); }
h3 { margin-top: 30px; font-size: 23px; }
.lede { max-width: 60ch; margin: 24px 0 0; color: var(--muted); font-size: clamp(18px, 2vw, 22px); line-height: 1.65; }
.hero-media { overflow: hidden; border-radius: var(--radius); box-shadow: var(--shadow); background: var(--surface-2); }
.hero-media img { width: 100%; aspect-ratio: 16 / 10; object-fit: cover; }
.hero-actions { margin-top: 30px; display: flex; flex-wrap: wrap; gap: 12px; }
.button {
  display: inline-flex;
  min-height: 48px;
  align-items: center;
  justify-content: center;
  padding: 0 19px;
  border: 1px solid var(--accent);
  border-radius: 12px;
  background: var(--accent);
  color: #f7faf8;
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
  transition: transform .18s ease, background .18s ease;
}
.button:hover { color: #ffffff; background: var(--accent-strong); transform: translateY(-1px); }
.button.secondary { background: transparent; color: var(--accent); }
.button.secondary:hover { color: var(--text); background: var(--accent-soft); }

.section { margin-top: 76px; }
.section > p, .section > .intro { max-width: 74ch; color: var(--muted); }
.summary-grid, .chapter-grid, .metric-grid, .source-grid { display: grid; gap: 20px; margin-top: 34px; }
.summary-grid { grid-template-columns: 1.25fr .75fr; }
.chapter-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.metric-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.source-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.panel {
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}
.panel.tinted { background: var(--accent-soft); }
.panel h2, .panel h3 { margin-top: 0; }
.panel p:last-child { margin-bottom: 0; }
.chapter { display: block; color: var(--text); text-decoration: none; transition: transform .18s ease, border-color .18s ease; }
.chapter:hover { transform: translateY(-2px); border-color: var(--accent); color: var(--text); }
.chapter small { color: var(--accent); font-weight: 720; }
.chapter h2 { margin-top: 10px; font-size: 30px; }
.chapter p { color: var(--muted); }
.metric strong { display: block; color: var(--accent); font-size: 38px; line-height: 1; }
.metric span { display: block; margin-top: 12px; color: var(--muted); font-size: 14px; }

.callout {
  margin: 32px 0;
  padding: 24px 26px;
  border-left: 5px solid var(--accent);
  border-radius: 0 var(--radius) var(--radius) 0;
  background: var(--accent-soft);
}
.callout strong { color: var(--accent-strong); }
.warning { border-left-color: var(--danger); }
.warning strong { color: var(--danger); }

.table-wrap { margin: 28px 0; overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius); background: var(--surface); }
table { width: 100%; min-width: 760px; border-collapse: collapse; }
th, td { padding: 17px 18px; text-align: left; vertical-align: top; border-bottom: 1px solid var(--line); }
th { color: var(--text); background: var(--surface-2); font-size: 14px; }
tr:last-child td { border-bottom: 0; }
td { color: var(--muted); }
td strong { color: var(--text); }

.flow { margin-top: 30px; display: grid; grid-template-columns: repeat(6, minmax(120px, 1fr)); gap: 10px; }
.flow-item { position: relative; min-height: 118px; padding: 18px; border-radius: 14px; background: var(--surface-2); }
.flow-item strong { display: block; color: var(--accent); }
.flow-item span { display: block; margin-top: 8px; color: var(--muted); font-size: 14px; line-height: 1.5; }
.check-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 18px; margin-top: 28px; }
.check { padding: 22px; border-top: 3px solid var(--accent); background: var(--surface); }
.check strong { display: block; }
.check p { color: var(--muted); margin-bottom: 0; }
.tag-row { display: flex; flex-wrap: wrap; gap: 9px; margin-top: 22px; }
.tag { padding: 7px 11px; border-radius: 10px; background: var(--surface-2); color: var(--muted); font-size: 13px; }
.source-list { padding-left: 20px; }
.source-list li { margin: 8px 0; }
.muted { color: var(--muted); }
.small { font-size: 14px; }
hr { margin: 72px 0; border: 0; border-top: 1px solid var(--line); }

.site-footer { border-top: 1px solid var(--line); }
.footer-inner { width: min(1180px, calc(100% - 40px)); margin: 0 auto; padding: 32px 0 48px; color: var(--muted); font-size: 14px; display: flex; justify-content: space-between; gap: 24px; }

@media (max-width: 900px) {
  .nav { align-items: flex-start; padding: 17px 0; }
  .nav-links { max-width: 68vw; overflow-x: auto; gap: 16px; }
  .hero { min-height: auto; grid-template-columns: 1fr; padding: 30px 0 12px; }
  .hero.compact { padding-top: 24px; }
  .hero-media { order: -1; }
  .summary-grid, .chapter-grid, .metric-grid, .source-grid, .check-grid { grid-template-columns: 1fr 1fr; }
  .flow { grid-template-columns: repeat(3, 1fr); }
}

@media (max-width: 620px) {
  body { font-size: 16px; }
  .page { width: min(100% - 28px, 1180px); padding-top: 36px; }
  .nav { width: min(100% - 28px, 1180px); display: block; }
  .nav-links { max-width: 100%; margin-top: 10px; }
  .summary-grid, .chapter-grid, .metric-grid, .source-grid, .check-grid { grid-template-columns: 1fr; }
  .flow { grid-template-columns: 1fr 1fr; }
  .panel { padding: 22px; }
  .footer-inner { width: min(100% - 28px, 1180px); display: block; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: .01ms !important; }
}

@media print {
  .site-header, .hero-actions { display: none; }
  body { background: #fff; color: #111; }
  .page { width: 100%; padding: 0; }
  .panel, .table-wrap { break-inside: avoid; box-shadow: none; }
}