:root {
  --blue: #1b3e8c;
  --blue-dark: #14306e;
  --blue-light: #2f56ad;
  --red: #c8102e;
  --bg: #f4f6fa;
  --text: #222;
  --muted: #667;
  --line: #e3e7ee;
  --serif: 'Source Han Serif SC', 'Songti SC', 'STSong', serif;
  --sans: 'PingFang SC', 'Microsoft YaHei', 'Hiragino Sans GB', sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body { background: #fff; color: var(--text); font-family: var(--sans); font-size: 14px; line-height: 1.7; -webkit-font-smoothing: antialiased; }
a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }
ul, ol { list-style: none; }
button, input { font-family: inherit; }

.wrap { max-width: 1200px; margin: 0 auto; padding: 0 20px; }

/* ---------- 顶部条 ---------- */
.topbar { background: #f2f4f8; border-bottom: 1px solid var(--line); font-size: 12px; color: #667; }
.topbar-inner { height: 34px; display: flex; align-items: center; justify-content: space-between; }
.topbar-date { letter-spacing: 0.02em; }
.topbar-links { display: flex; align-items: center; gap: 8px; }
.topbar-links i { color: #c4ccd8; font-style: normal; }
.topbar-links a:hover { color: var(--blue); }

/* ---------- 页头 ---------- */
.header { position: relative; background: #fff; overflow: hidden; }
.header-bg {
  position: absolute;
  inset: 0;
  background: url('/landing/img/scene-research.jpg') right center / cover no-repeat;
  opacity: 0.18;
  mask-image: linear-gradient(90deg, transparent 35%, #000 100%);
}
.header-inner {
  position: relative;
  min-height: 118px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}
.brand { display: flex; align-items: center; gap: 18px; }
.brand-mark { width: 72px; height: 72px; color: var(--blue); flex: none; }
.brand-mark svg { width: 100%; height: 100%; }
.brand-mark.small { width: 54px; height: 54px; color: #fff; }
.brand-name { display: flex; flex-direction: column; gap: 4px; }
.brand-name b { font-family: var(--serif); font-size: 30px; letter-spacing: 0.12em; color: var(--blue); font-weight: 700; }
.brand-name i { font-style: normal; font-size: 10px; letter-spacing: 0.16em; color: #7b8aa3; }

.header-contact { text-align: right; display: flex; flex-direction: column; gap: 6px; }
.header-contact span { font-size: 12px; color: #6c7a90; letter-spacing: 0.08em; }
.header-contact a { font-size: 13px; color: var(--blue); border-bottom: 1px solid transparent; }
.header-contact a:hover { border-bottom-color: var(--blue); }

/* ---------- 导航 ---------- */
.nav { background: var(--blue); position: sticky; top: 0; z-index: 50; }
.nav-inner { display: flex; align-items: center; height: 48px; }
.nav-inner > a {
  color: #fff;
  font-size: 15px;
  padding: 0 22px;
  height: 48px;
  line-height: 48px;
  letter-spacing: 0.04em;
  white-space: nowrap;
  transition: background 0.2s;
}
.nav-inner > a:hover, .nav-inner > a.nav-home { background: var(--blue-dark); }
.nav-search { margin-left: auto; display: flex; align-items: center; background: #fff; height: 30px; width: 230px; padding-left: 12px; }
.nav-search input { border: 0; outline: 0; width: 100%; font-size: 13px; color: #333; }
.nav-search button { border: 0; background: none; width: 40px; height: 30px; color: var(--blue); cursor: pointer; display: grid; place-items: center; }
.nav-search button svg { width: 18px; height: 18px; }
.nav-toggle { display: none; background: none; border: 0; cursor: pointer; padding: 10px; }
.nav-toggle span { display: block; width: 20px; height: 2px; background: #fff; margin: 4px 0; }

/* ---------- 页脚 ---------- */
.footer { background: var(--blue-dark); color: rgba(255, 255, 255, 0.82); margin-top: 50px; }
.footer-inner { padding: 42px 20px 22px; display: grid; grid-template-columns: 1fr 1fr; gap: 30px 60px; }
.footer-brand { display: flex; align-items: center; gap: 16px; }
.footer-brand b { display: block; font-family: var(--serif); font-size: 21px; letter-spacing: 0.1em; color: #fff; }
.footer-brand span { display: block; font-size: 9px; letter-spacing: 0.14em; color: rgba(255, 255, 255, 0.55); margin-top: 4px; }
.footer-meta { align-self: center; font-size: 12px; line-height: 2; color: rgba(255, 255, 255, 0.65); }
.footer-bottom {
  grid-column: 1 / -1;
  border-top: 1px solid rgba(255, 255, 255, 0.14);
  padding-top: 16px;
  margin-top: 10px;
  display: flex;
  justify-content: space-between;
  font-size: 11px;
  color: rgba(255, 255, 255, 0.5);
}

/* ---------- 回到锚点时留出导航高度 ---------- */
section[id], div[id] { scroll-margin-top: 60px; }