/* ============================================================
   沉陷区的地质记忆 · 项目门户
   美术参考：DJI 官网（大字号 / 大留白 / 精致数据陈列）
   配色：纯白极简 —— 白底 + 墨色 + 单一赭石强调
   ============================================================ */

:root {
  --paper: #ffffff;
  --paper-2: #f8f8f9;    /* 极浅交替底（中性灰，与冷灰文字同族） */
  --ink: #16181d;
  --sub: #646c76;
  --dim: #767d86;   /* 对比度 ≥4.5:1 */
  --amber: #a86a24;
  --amber-soft: #cf9c5c;
  --teal: #2a8f8c;
  --line: rgba(22, 24, 29, .09);
  --shadow: 0 14px 44px rgba(22, 24, 29, .07);
  --font: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei",
          "Noto Sans SC", -apple-system, "Segoe UI", sans-serif;
  --mono: "SF Mono", "JetBrains Mono", Consolas, monospace;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  background: var(--paper); color: var(--ink);
  font-family: var(--font);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
::selection { background: var(--amber); color: #fff; }
img { max-width: 100%; height: auto; display: block; }
a { color: inherit; text-decoration: none; }

/* ---------- 顶部导航 ---------- */
.nav {
  position: fixed; inset: 0 0 auto 0; z-index: 100;
  display: flex; align-items: center; justify-content: space-between;
  padding: 0 44px; height: 64px;
  transition: background .35s, backdrop-filter .35s, box-shadow .35s;
}
.nav.scrolled {
  background: rgba(255, 255, 255, .86);
  backdrop-filter: blur(14px);
  box-shadow: 0 1px 0 var(--line);
}
.nav-logo { display: flex; align-items: baseline; gap: 10px; font-weight: 700; }
.nav-logo .cn { font-size: 17px; letter-spacing: .12em; }
.nav-logo .en { font-size: 10px; color: var(--dim); letter-spacing: .28em;
  font-family: var(--mono); }
/* 未滚动时浮在影像上：导航反白 */
.nav:not(.scrolled) .nav-logo .cn { color: #fff; }
.nav:not(.scrolled) .nav-logo .en { color: rgba(255,255,255,.6); }
.nav:not(.scrolled) .nav-links a { color: rgba(255,255,255,.82); }
.nav:not(.scrolled) .nav-links a:hover { color: #fff; }
.nav:not(.scrolled) .nav-links .wiki-link { color: #e8b96f; }
.nav-links { display: flex; gap: 34px; font-size: 13px; color: var(--sub); }
.nav-links a { position: relative; padding: 4px 0; transition: color .25s; }
.nav-links a:hover { color: var(--ink); }
.nav-links a::after {
  content: ""; position: absolute; left: 0; bottom: -2px; width: 0; height: 2px;
  background: var(--amber); transition: width .3s; border-radius: 2px;
}
.nav-links a:hover::after { width: 100%; }
.nav-links .wiki-link { color: var(--amber); font-weight: 600; }

/* ---------- 首屏 Hero ---------- */
.hero {
  position: relative; height: 100vh; min-height: 640px;
  display: flex; align-items: flex-end;
  overflow: hidden;
}
@supports (height: 100svh) { .hero { height: 100svh; } }
.hero-bg {
  position: absolute; inset: -8% 0; z-index: 0;
  background: url("../img/hero_contour.webp") center 42% / cover no-repeat;
  will-change: transform;
}
/* 电影感渐变压暗：顶部轻、底部深，无边界的柔和过渡 */
.hero::after {
  content: ""; position: absolute; inset: 0; z-index: 1;
  background:
    linear-gradient(180deg,
      rgba(10, 14, 18, .34) 0%, rgba(10, 14, 18, 0) 30%,
      rgba(10, 14, 18, .10) 52%, rgba(10, 14, 18, .62) 82%,
      rgba(10, 14, 18, .82) 100%);
}
.hero-inner {
  position: relative; z-index: 2; width: 100%;
  padding: 0 44px 72px; max-width: 1440px; margin: 0 auto;
}
.hero-eyebrow {
  font-size: 13px; letter-spacing: .3em; color: #e8b96f;
  font-family: var(--mono); margin-bottom: 22px; font-weight: 600;
  text-shadow: 0 1px 12px rgba(0,0,0,.4);
}
.hero h1 {
  font-size: clamp(44px, 7.6vw, 112px);
  line-height: 1.05; font-weight: 800; letter-spacing: .02em;
  margin-bottom: 24px; color: #ffffff;
  text-shadow: 0 2px 30px rgba(0,0,0,.42);
}
.hero-sub {
  font-size: clamp(14px, 1.5vw, 19px); color: rgba(255,255,255,.86);
  max-width: 640px; line-height: 1.8; margin-bottom: 34px;
  text-shadow: 0 1px 14px rgba(0,0,0,.45);
}
.hero-sub .mono { font-family: var(--mono); font-size: .76em;
  letter-spacing: .18em; display: block; margin-top: 12px;
  color: rgba(255,255,255,.6); }
.hero-cta { display: flex; gap: 16px; flex-wrap: wrap; }
.btn {
  display: inline-flex; align-items: center; gap: 10px;
  font-size: 14px; font-weight: 600; letter-spacing: .06em;
  padding: 15px 34px; border-radius: 999px;
  transition: transform .25s, box-shadow .25s, background .25s, color .25s,
              border-color .25s;
}
.btn-primary { background: var(--ink); color: #fff; }
.btn-primary:hover { transform: translateY(-2px);
  box-shadow: 0 14px 36px rgba(22,24,29,.24); }
.btn-ghost { border: 1.5px solid rgba(22,24,29,.30); color: var(--ink); }
.btn-ghost:hover { border-color: var(--amber); color: var(--amber);
  transform: translateY(-2px); }
/* Hero 影像上的按钮反白 */
.hero .btn-primary { background: #ffffff; color: #16181d; }
.hero .btn-primary:hover { box-shadow: 0 14px 36px rgba(0,0,0,.35); }
.hero .btn-ghost { border-color: rgba(255,255,255,.55); color: #fff; }
.hero .btn-ghost:hover { border-color: #e8b96f; color: #e8b96f; }
/* 键盘焦点可见性（无障碍） */
:focus-visible { outline: 2px solid var(--amber); outline-offset: 3px; }


/* ---------- 通用区块 ---------- */
.section { position: relative; padding: 130px 44px; }
.section.alt { background: var(--paper-2); }
.wrap { max-width: 1240px; margin: 0 auto; }
.sec-head { margin-bottom: 64px; }
.sec-title {
  font-size: clamp(30px, 4.6vw, 58px); font-weight: 800; line-height: 1.15;
  letter-spacing: .02em;
}
.sec-title .thin { color: var(--sub); font-weight: 300; }
.sec-desc { margin-top: 22px; color: var(--sub); font-size: 15px;
  line-height: 1.9; max-width: 680px; }
.sec-desc b, .sec-desc strong { color: var(--ink); font-weight: 600; }

/* 入场动画 */
.reveal { opacity: 0; transform: translateY(36px);
  transition: opacity .9s cubic-bezier(.2,.6,.2,1), transform .9s cubic-bezier(.2,.6,.2,1); }
.reveal.in { opacity: 1; transform: none; }

/* ---------- 概念区 ---------- */
.concept { text-align: center; }
.concept .quote {
  font-size: clamp(27px, 4.2vw, 52px); font-weight: 800; line-height: 1.55;
  max-width: 1020px; margin: 0 auto;
}
.concept .quote em { font-style: normal; color: var(--amber); }
.concept .quote .teal { color: var(--teal); }
.concept p.body {
  margin: 48px auto 0; max-width: 720px; color: var(--sub);
  font-size: 15px; line-height: 2.25;
}
.concept p.body strong { color: var(--ink); font-weight: 600; }

/* ---------- 数据规格表 ---------- */
.spec-grid { display: grid; grid-template-columns: repeat(4, 1fr);
  border-top: 1px solid var(--line); }
.spec {
  padding: 38px 30px 34px; border-bottom: 1px solid var(--line);
  border-right: 1px solid var(--line);
  transition: background .3s;
}
.spec:first-child { border-left: 1px solid var(--line); }
.spec:hover { background: var(--paper-2); }
.spec .num {
  font-size: clamp(34px, 3.6vw, 54px); font-weight: 800; line-height: 1;
  font-variant-numeric: tabular-nums; color: var(--ink);
}
.spec .num small { font-size: .40em; font-weight: 600; color: var(--sub);
  margin-left: 6px; }
.spec .lab { margin-top: 14px; font-size: 13px; color: var(--sub);
  line-height: 1.8; }
.spec.amber { border-top: 2px solid var(--amber); }
.spec.amber .num { color: var(--amber); }
.spec.teal { border-top: 2px solid var(--teal); }
.spec.teal .num { color: var(--teal); }

/* ---------- 图文双栏 ---------- */
.split {
  display: grid; grid-template-columns: 1.05fr .95fr; gap: 72px;
  align-items: center;
}
.split.rev { grid-template-columns: .95fr 1.05fr; }
.figure {
  position: relative; overflow: hidden; border-radius: 10px;
  border: 1px solid var(--line); background: #fff;
}
.figure img { transition: transform 1.2s cubic-bezier(.2,.6,.2,1); }
.figure:hover img { transform: scale(1.03); }
.figure figcaption {
  padding: 13px 18px; font-size: 11px; color: var(--sub);
  border-top: 1px solid var(--line); background: #fff;
  font-family: var(--mono); letter-spacing: .06em;
}
.fact-list { margin-top: 8px; border-top: 1px solid var(--line); }
.fact {
  display: grid; grid-template-columns: 118px 1fr; gap: 22px;
  padding: 20px 4px; border-bottom: 1px solid var(--line);
  font-size: 14px; line-height: 1.95;
}
.fact .k { color: var(--amber); font-family: var(--mono); font-size: 12px;
  letter-spacing: .10em; padding-top: 4px; font-weight: 600; }
.fact .v { color: var(--sub); }
.fact .v b { color: var(--ink); font-weight: 600; }

/* ---------- 实景照片带 ---------- */
.photo-band {
  position: relative; margin-top: 88px; border-radius: 10px;
  overflow: hidden; border: 1px solid var(--line);
}
.photo-band img { width: 100%; height: 62vh; min-height: 420px;
  object-fit: cover; }
.photo-band .quote {
  position: absolute; left: 44px; bottom: 44px; z-index: 2;
  color: #fff; font-size: clamp(24px, 3.2vw, 42px); font-weight: 800;
  text-shadow: 0 2px 22px rgba(0,0,0,.45); line-height: 1.4;
}
.photo-band .quote span {
  display: block; font-size: 14px; font-weight: 400; margin-top: 12px;
  opacity: .92;
}
.photo-band::after {
  content: ""; position: absolute; inset: 0; z-index: 1;
  background: linear-gradient(180deg, rgba(0,0,0,0) 42%, rgba(0,0,0,.52));
}
.photo-credit {
  position: absolute; right: 16px; bottom: 12px; z-index: 2;
  font-size: 10px; color: rgba(255,255,255,.82);
  font-family: var(--mono); letter-spacing: .04em;
  text-shadow: 0 1px 8px rgba(0,0,0,.5);
}
.photo-duo {
  display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 12px;
}
.photo-duo .pb {
  position: relative; border-radius: 10px; overflow: hidden;
  border: 1px solid var(--line);
}
.photo-duo img { width: 100%; height: 340px; object-fit: cover;
  transition: transform 1.2s cubic-bezier(.2,.6,.2,1); }
.photo-duo .pb:hover img { transform: scale(1.03); }
.photo-duo .photo-credit { font-size: 9.5px; }

/* ---------- 历史时间轴 ---------- */
.timeline { margin-top: 76px; position: relative; }
.timeline::before {
  content: ""; position: absolute; left: 8px; top: 6px; bottom: 6px;
  width: 2px; background: var(--line); border-radius: 2px;
}
.tl-item { position: relative; padding: 0 0 38px 46px; }
.tl-item::before {
  content: ""; position: absolute; left: 2px; top: 7px; width: 12px;
  height: 12px; border-radius: 50%; background: var(--paper);
  border: 3px solid var(--amber);
}
.tl-item.teal::before { border-color: var(--teal); }
.tl-year { font-family: var(--mono); font-size: 13px; color: var(--amber);
  letter-spacing: .18em; margin-bottom: 8px; font-weight: 700; }
.tl-item.teal .tl-year { color: var(--teal); }
.tl-body { font-size: 14.5px; color: var(--sub); line-height: 1.95;
  max-width: 780px; }
.tl-body b { color: var(--ink); font-weight: 600; }

/* ---------- 行动 ---------- */
.days { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px;
  margin-top: 60px; }
.day {
  background: #fff; border: 1px solid var(--line); border-radius: 10px;
  padding: 24px 18px; min-height: 216px; display: flex; flex-direction: column;
  transition: transform .3s, box-shadow .3s, border-color .3s;
}
.day:hover { transform: translateY(-5px); box-shadow: var(--shadow);
  border-color: var(--amber-soft); }
.day .d { font-family: var(--mono); font-size: 11px; color: var(--amber);
  letter-spacing: .2em; font-weight: 700; }
.day .t { font-size: 16px; font-weight: 700; margin-top: 14px; }
.day .b { font-size: 12px; color: var(--sub); line-height: 1.85; margin-top: 10px; }

/* ---------- 研究方法（分隔行） ---------- */
.method-rows { margin-top: 60px; border-top: 1px solid var(--line); }
.mrow {
  display: grid; grid-template-columns: 56px 170px 1fr; gap: 24px;
  align-items: center; padding: 26px 6px;
  border-bottom: 1px solid var(--line);
  transition: background .25s;
}
.mrow:hover { background: var(--paper-2); }
.mrow i { font-size: 26px; color: var(--amber); }
.mrow .mt { font-size: 17px; font-weight: 700; }
.mrow .mb { font-size: 13px; color: var(--sub); line-height: 1.9; }

/* ---------- 团队 ---------- */
.teams { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px;
  margin-top: 60px; }
.team {
  background: #fff; border: 1px solid var(--line); border-radius: 10px;
  padding: 32px 28px; transition: transform .3s, box-shadow .3s;
}
.team:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.team .no { font-family: var(--mono); font-size: 11px; color: var(--dim);
  letter-spacing: .2em; font-weight: 600; }
.team .t { font-size: 19px; font-weight: 700; margin-top: 12px; }
.team .m { font-size: 13px; color: var(--amber); margin-top: 12px;
  line-height: 1.8; font-weight: 600; }
.team .b { font-size: 12.5px; color: var(--sub); line-height: 1.9;
  margin-top: 12px; }
.team-wide { grid-column: 1 / -1; background: var(--paper-2); }

/* ---------- 成果 ---------- */
.outcomes { display: grid; grid-template-columns: repeat(2, 1fr); gap: 12px;
  margin-top: 60px; }
.outcome {
  background: #fff; border: 1px solid var(--line); border-radius: 10px;
  padding: 36px 32px; display: flex; gap: 26px; align-items: flex-start;
  transition: transform .3s, box-shadow .3s, border-color .3s;
}
.outcome:hover { transform: translateY(-4px); box-shadow: var(--shadow);
  border-color: var(--amber-soft); }
.outcome .big { font-size: 42px; font-weight: 800; color: var(--amber);
  line-height: 1; font-variant-numeric: tabular-nums; white-space: nowrap; }
.outcome .big small { font-size: 14px; color: var(--sub); font-weight: 600; }
.outcome .t { font-size: 17px; font-weight: 700; }
.outcome .b { font-size: 12.5px; color: var(--sub); line-height: 1.9;
  margin-top: 8px; }

/* ---------- Wiki CTA 横幅 ---------- */
.wiki-banner {
  position: relative; overflow: hidden; border-radius: 12px;
  border: 1px solid var(--line);
  background: url("../img/hero_contour.webp") center 60% / cover no-repeat;
}
.wiki-banner::before { content: ""; position: absolute; inset: 0;
  background: rgba(255, 255, 255, .80); }
.wiki-banner .inner {
  position: relative; z-index: 1; padding: 108px 44px; text-align: center;
}
.wiki-banner h3 { font-size: clamp(26px, 3.4vw, 44px); font-weight: 800; }
.wiki-banner p { color: var(--sub); margin: 20px auto 40px;
  max-width: 580px; font-size: 14.5px; line-height: 2.05; }

/* ---------- 页脚（浅色收束） ---------- */
footer {
  padding: 76px 44px 48px; background: var(--paper-2);
  border-top: 1px solid var(--line);
}
.foot-grid { max-width: 1240px; margin: 0 auto; display: grid;
  grid-template-columns: 1.4fr 1fr 1fr; gap: 44px; }
.foot-grid h5 { font-size: 11px; color: var(--dim); letter-spacing: .26em;
  margin-bottom: 18px; font-family: var(--mono); }
.foot-grid p, .foot-grid a { font-size: 13px; color: var(--sub);
  line-height: 2.15; display: block; }
.foot-grid a:hover { color: var(--amber); }
.foot-brand { font-size: 20px; font-weight: 800; letter-spacing: .06em;
  margin-bottom: 14px; color: var(--ink); }
.copyright { max-width: 1240px; margin: 54px auto 0; padding-top: 24px;
  border-top: 1px solid var(--line); font-size: 11px;
  color: var(--dim); line-height: 2.1; }

/* ---------- 响应式 ---------- */
/* 移动端首屏：图在上、文在下，彻底分离 */
@media (max-width: 860px) {
  .hero { display: block; height: auto; min-height: 0; overflow: visible; }
  .hero-bg { position: relative; inset: 0; height: 54svh; min-height: 320px;
    background-position: center 40%; transform: none !important; }
  .hero::after { display: none; }
  .hero-inner { padding: 42px 20px 54px; }
  .hero-eyebrow { color: var(--amber); text-shadow: none; }
  .hero h1 { color: var(--ink); text-shadow: none; }
  .hero-sub { color: var(--sub); text-shadow: none; }
  .hero-sub .mono { color: var(--dim); }
      .hero .btn-primary { background: var(--ink); color: #fff; }
  .hero .btn-primary:hover { box-shadow: 0 10px 26px rgba(22,24,29,.22); }
  .hero .btn-ghost { border-color: rgba(22,24,29,.30); color: var(--ink); }
  .hero .btn-ghost:hover { border-color: var(--amber); color: var(--amber); }
  .hero-cta .btn { width: 100%; justify-content: center; }
  /* 概念区左对齐 */
  .concept { text-align: left; }
  .concept .quote { max-width: none; }
  .concept p.body { margin-left: 0; }
  /* 照片带：来源信息移到图下，不再与引用语重叠 */
  .photo-band .quote { left: 18px; right: 18px; bottom: 18px;
    font-size: 20px; }
  .photo-credit { position: static; color: var(--dim); text-shadow: none;
    padding: 10px 14px; font-size: 10px; }
}
@media (max-width: 1080px) {
  .days { grid-template-columns: repeat(4, 1fr); }
  .mrow { grid-template-columns: 48px 150px 1fr; }
  .teams { grid-template-columns: repeat(2, 1fr); }
  .split, .split.rev { grid-template-columns: 1fr; gap: 44px; }
  .photo-duo { grid-template-columns: 1fr; }
  .photo-duo img { height: auto; aspect-ratio: 3 / 2; }
  .spec-grid { grid-template-columns: repeat(2, 1fr); }
  .spec { border-left: 1px solid var(--line); }
  .spec:nth-child(2n) { border-left: none; }
}
@media (max-width: 680px) {
  .nav { padding: 0 20px; }
  .nav-links { gap: 18px; font-size: 12px; }
  .nav-links a:nth-child(-n+3) { display: none; }
  .section { padding: 84px 20px; }
  .hero { min-height: 0; }
  .days { grid-template-columns: repeat(2, 1fr); }
  .day { min-height: 0; }
  .fact { grid-template-columns: 1fr; gap: 4px; padding: 16px 2px; }
  .mrow { grid-template-columns: 40px 1fr; }
  .mrow .mb { grid-column: 2; }
  .photo-band img { height: 46vh; min-height: 300px; }
  .photo-duo { grid-template-columns: 1fr; }
  .photo-duo img { height: 220px; }
  .outcomes { grid-template-columns: 1fr; }
  .teams { grid-template-columns: 1fr; }
  .foot-grid { grid-template-columns: 1fr; }
}

/* ---------- 减弱动效（无障碍） ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal { opacity: 1; transform: none; transition: none; }
  .hero-bg { transform: none !important; }
  * { transition-duration: .01ms !important; }
}