:root {
  --primary: #1f3a5f;
  --primary-deep: #16283f;
  --accent: #d08c3c;
  --bg: #f4f6f8;
  --surface: #ffffff;
  --ink: #16202c;
  --muted: #55616f;
  --line: rgba(22, 32, 44, 0.14);
  --serif: Georgia, "Songti SC", SimSun, "Times New Roman", serif;
  --sans: -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
  --maxw: 1140px;
  --gutter: 24px;
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.78;
  -webkit-font-smoothing: antialiased;
}

img {
  max-width: 100%;
  height: auto;
}

a {
  color: inherit;
  text-decoration: none;
}

h1,
h2,
h3 {
  margin: 0;
  font-family: var(--serif);
  font-weight: 600;
  line-height: 1.22;
  letter-spacing: 0.01em;
}

p {
  margin: 0 0 1em;
}

p:last-child {
  margin-bottom: 0;
}

.wrap {
  width: min(100% - var(--gutter) * 2, var(--maxw));
  margin-inline: auto;
}

/* ---------- 页头 ---------- */

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(244, 246, 248, 0.94);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(8px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 76px;
}

.brand-logo {
  display: block;
  height: 46px;
  width: auto;
}

.nav {
  display: flex;
  align-items: center;
  gap: 34px;
  font-size: 15px;
}

.nav a {
  position: relative;
  padding: 6px 0;
  color: var(--ink);
}

.nav a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 0;
  height: 2px;
  background: var(--accent);
  transition: width 0.25s ease;
}

.nav a:hover::after,
.nav a:focus-visible::after {
  width: 100%;
}

.nav-toggle {
  display: none;
  width: 42px;
  height: 42px;
  padding: 10px;
  background: none;
  border: 1px solid var(--line);
  border-radius: 2px;
  cursor: pointer;
}

.nav-toggle span {
  display: block;
  height: 2px;
  margin: 4px 0;
  background: var(--primary);
}

/* ---------- Hero ---------- */

.hero {
  position: relative;
  padding: clamp(64px, 9vw, 108px) 0 clamp(56px, 8vw, 92px);
  border-bottom: 1px solid var(--line);
  overflow: hidden;
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) minmax(0, 0.9fr);
  gap: clamp(32px, 6vw, 80px);
  align-items: end;
}

.eyebrow {
  margin-bottom: 22px;
  font-size: 12px;
  letter-spacing: 0.32em;
  text-transform: uppercase;
  color: var(--accent);
}

.hero-title {
  margin-left: -3px;
  font-size: clamp(34px, 4.4vw, 60px);
  color: var(--ink);
}

.hero-title-line {
  display: block;
  padding-left: 1.1em;
  color: var(--primary);
}

.hero-lead {
  max-width: 34em;
  margin: 28px 0 34px;
  font-size: 17px;
  color: var(--muted);
}

.btn {
  display: inline-block;
  padding: 14px 30px;
  background: var(--primary);
  color: #fff;
  font-size: 15px;
  letter-spacing: 0.06em;
  border-bottom: 3px solid var(--accent);
  transition: background 0.25s ease, transform 0.25s ease;
}

.btn:hover,
.btn:focus-visible {
  background: var(--primary-deep);
  transform: translateY(-2px);
}

.hero-side {
  border-top: 2px solid var(--primary);
  padding-top: 18px;
}

.hero-side-label {
  margin-bottom: 14px;
  font-size: 13px;
  letter-spacing: 0.18em;
  color: var(--muted);
}

.facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px 20px;
  margin: 0;
}

.fact dt {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.fact dd {
  margin: 2px 0 0;
  font-family: var(--serif);
  font-size: 19px;
  color: var(--primary);
}

/* ---------- 通用区块 ---------- */

.section {
  padding: clamp(56px, 8vw, 96px) 0;
}

.section-alt {
  background: var(--surface);
  border-block: 1px solid var(--line);
}

.section-index {
  margin-bottom: 10px;
  font-family: var(--serif);
  font-size: 14px;
  letter-spacing: 0.2em;
  color: var(--accent);
}

.section-head h2 {
  font-size: clamp(26px, 3vw, 38px);
  color: var(--primary);
}

.section-desc {
  max-width: 40em;
  margin-top: 18px;
  color: var(--muted);
}

/* ---------- 滚动显现 ---------- */

.reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.reveal.is-visible {
  opacity: 1;
  transform: none;
}

/* ---------- 页脚 ---------- */

.site-footer {
  padding: 34px 0;
  background: var(--primary-deep);
  color: rgba(255, 255, 255, 0.82);
  font-size: 14px;
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.footer-inner p {
  margin: 0;
}

.footer-icp {
  color: rgba(255, 255, 255, 0.62);
}

/* ---------- 响应式 ---------- */

@media (max-width: 900px) {
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 40px;
  }

  .hero-side {
    max-width: 520px;
  }
}

@media (max-width: 768px) {
  :root {
    --gutter: 20px;
  }

  .header-inner {
    min-height: 66px;
  }

  .brand-logo {
    height: 40px;
  }

  .nav-toggle {
    display: block;
  }

  .nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    flex-direction: column;
    align-items: flex-start;
    gap: 0;
    padding: 4px var(--gutter) 18px;
    background: var(--surface);
    border-bottom: 1px solid var(--line);
    box-shadow: 0 12px 24px rgba(16, 24, 34, 0.08);
    display: none;
  }

  .nav-open .nav {
    display: flex;
  }

  .nav a {
    width: 100%;
    padding: 13px 0;
    border-bottom: 1px solid var(--line);
  }

  .nav a:last-child {
    border-bottom: 0;
  }

  .hero {
    padding-top: 48px;
  }

  .hero-title {
    font-size: 30px;
  }

  .hero-title-line {
    padding-left: 0.6em;
  }

  .hero-lead {
    font-size: 16px;
  }

  .facts {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 420px) {
  .facts {
    grid-template-columns: 1fr;
  }
}

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

  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
}