:root{
    --bg:#14110F;
    --bg-2:#1B1714;
    --bg-3:#221C18;
    --ink:#F2ECE2;
    --ink-soft:#B8AE9F;
    --ink-faint:#7C7368;
    --line:rgba(242,236,226,.12);
    --line-strong:rgba(242,236,226,.22);
    /* 艳丽饱和色：生皮(金) → 鞣制(焰橙) → 整饰(玫红) → 器物(紫晶) */
    --c1:#E8B84B;
    --c2:#E2703A;
    --c3:#C8415B;
    --c4:#8E5BC4;
    --serif:"Songti SC","STSong","SimSun","Noto Serif SC","Source Han Serif SC",Georgia,"Times New Roman",serif;
    --sans:-apple-system,BlinkMacSystemFont,"PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
    --nav-h:64px;
    --ease:cubic-bezier(.22,.61,.36,1);
  }

  *{box-sizing:border-box;}
  html{scroll-behavior:smooth;}
  body{
    margin:0;
    background:var(--bg);
    color:var(--ink);
    font-family:var(--serif);
    -webkit-font-smoothing:antialiased;
    text-rendering:optimizeLegibility;
    line-height:1.6;
  }
  a{color:inherit;text-decoration:none;}
  .skip-link{position:absolute;left:-9999px;top:0;background:var(--ink);color:var(--bg);padding:8px 14px;z-index:99;}
  .skip-link:focus{left:12px;top:12px;}

  .container{max-width:1080px;margin:0 auto;padding:0 28px;}
  .container--narrow{max-width:720px;}

  /* ---------- 导航 ---------- */
  .nav{
    position:fixed;top:0;left:0;right:0;height:var(--nav-h);z-index:50;
    display:flex;align-items:center;
    background:linear-gradient(to bottom, rgba(20,17,15,.85), rgba(20,17,15,0));
    transition:background .4s var(--ease), border-color .4s var(--ease);
    border-bottom:1px solid transparent;
  }
  .nav.is-scrolled{
    background:rgba(20,17,15,.92);
    -webkit-backdrop-filter:saturate(140%) blur(10px);
    backdrop-filter:saturate(140%) blur(10px);
    border-bottom:1px solid var(--line);
  }
  .nav__inner{max-width:1080px;margin:0 auto;padding:0 28px;width:100%;display:flex;align-items:center;justify-content:space-between;}
  .nav__brand{display:flex;align-items:baseline;gap:10px;}
  .nav__mark{font-family:var(--serif);font-size:1.4rem;font-weight:600;letter-spacing:.02em;color:var(--ink);}
  .nav__sub{font-family:var(--sans);font-size:.72rem;letter-spacing:.32em;color:var(--ink-faint);text-transform:uppercase;}
  .nav__menu{display:flex;gap:30px;list-style:none;margin:0;padding:0;}
  .nav__link{font-family:var(--sans);font-size:.86rem;letter-spacing:.12em;color:var(--ink-soft);transition:color .25s var(--ease);}
  .nav__link:hover{color:var(--ink);}

  /* ---------- 首屏 ---------- */
  .hero{
    position:relative;display:flex;align-items:center;justify-content:center;
    text-align:center;overflow:hidden;padding:calc(var(--nav-h) + 70px) 28px 70px;
  }
  .hero__glow{
    position:absolute;inset:0;z-index:0;pointer-events:none;
    background:
      radial-gradient(58% 46% at 50% 34%, rgba(232,184,75,.20), transparent 70%),
      radial-gradient(46% 40% at 72% 62%, rgba(200,65,91,.16), transparent 72%),
      radial-gradient(40% 38% at 26% 70%, rgba(142,91,196,.14), transparent 72%);
  }
  .hero__inner{position:relative;z-index:1;max-width:820px;}
  .eyebrow{
    font-family:var(--sans);font-size:.74rem;letter-spacing:.42em;text-transform:uppercase;
    color:var(--ink-faint);margin:0 0 26px;
  }
  .hero__title{
    font-family:var(--serif);font-weight:500;
    font-size:clamp(2.4rem,6.2vw,4.6rem);line-height:1.18;letter-spacing:.01em;
    margin:0;color:var(--ink);
  }
  .hero__lead{
    font-family:var(--serif);font-weight:400;
    font-size:clamp(1.02rem,2.1vw,1.3rem);line-height:1.75;color:var(--ink-soft);
    max-width:40rem;margin:30px auto 0;
  }
  .hero__visual{position:relative;z-index:1;margin:46px auto 0;max-width:780px;}
  .hero__visual img{
    display:block;width:100%;height:auto;border-radius:16px;
    -webkit-mask-image:radial-gradient(115% 105% at 50% 46%, #000 58%, transparent 97%);
    mask-image:radial-gradient(115% 105% at 50% 46%, #000 58%, transparent 97%);
  }
  .hero__scroll{
    position:absolute;bottom:30px;left:50%;transform:translateX(-50%);z-index:1;
    font-family:var(--sans);font-size:.7rem;letter-spacing:.3em;color:var(--ink-faint);
    writing-mode:vertical-rl;
  }

  /* ---------- 全链路 ---------- */
  .chain{position:relative;padding:30px 0 40px;}
  .chain__head{text-align:center;padding:60px 0 20px;}
  .chain__head h2{font-family:var(--serif);font-weight:500;font-size:clamp(1.6rem,3.6vw,2.3rem);margin:0;color:var(--ink);}
  .chain__head p{font-family:var(--serif);color:var(--ink-soft);max-width:34rem;margin:16px auto 0;}

  .spine{position:absolute;left:46px;top:120px;bottom:60px;width:2px;background:var(--line);}
  .spine__fill{position:absolute;top:0;left:0;width:100%;height:0;background:linear-gradient(to bottom,var(--c1),var(--c2),var(--c3),var(--c4));transition:height .15s linear;}

  .stage{
    position:relative;display:grid;grid-template-columns:92px 1fr;gap:34px;
    padding:54px 0;border-top:1px solid var(--line);align-items:stretch;
  }
  .stage:first-of-type{border-top:none;}
  .stage__node{
    position:relative;display:flex;flex-direction:column;align-items:center;
  }
  .stage__dot{
    width:16px;height:16px;border-radius:50%;margin-top:8px;
    background:var(--bg-3);border:2px solid var(--line-strong);
    transition:background .5s var(--ease),border-color .5s var(--ease),box-shadow .5s var(--ease),transform .5s var(--ease);
  }
  .stage__no{font-family:var(--serif);font-size:2.1rem;font-weight:500;color:var(--ink-faint);transition:color .5s var(--ease);}
  .stage__body{display:grid;grid-template-columns:1fr;gap:22px;}
  .stage__text h3{font-family:var(--serif);font-weight:600;font-size:clamp(1.5rem,3.4vw,2rem);margin:0 0 14px;color:var(--ink);letter-spacing:.04em;}
  .stage__text p{font-family:var(--serif);color:var(--ink-soft);font-size:1.05rem;line-height:1.78;margin:0;max-width:38rem;}
  .stage__panel{
    position:relative;aspect-ratio:16/7;border-radius:14px;overflow:hidden;
    background:var(--bg-3);
    filter:grayscale(.6) brightness(.62);opacity:.5;
    transition:filter .7s var(--ease),opacity .7s var(--ease),box-shadow .7s var(--ease),transform .7s var(--ease);
    display:flex;align-items:flex-end;padding:18px 20px;
  }
  .stage__panel img{
    position:absolute;inset:0;width:100%;height:100%;object-fit:cover;display:block;
  }
  .stage__panel::after{
    content:"";position:absolute;inset:0;
    background:radial-gradient(60% 60% at 30% 25%, rgba(255,255,255,.22), transparent 60%);
  }
  .stage__panel span{
    position:relative;z-index:1;font-family:var(--sans);font-size:.72rem;letter-spacing:.28em;
    text-transform:uppercase;color:rgba(255,255,255,.82);
  }

  /* 点亮态 */
  .stage.is-in .stage__dot{
    background:var(--stage);border-color:var(--stage);
    box-shadow:0 0 0 5px color-mix(in srgb,var(--stage) 22%, transparent), 0 0 22px color-mix(in srgb,var(--stage) 60%, transparent);
    transform:scale(1.12);
  }
  .stage.is-in .stage__no{color:var(--stage);}
  .stage.is-in .stage__panel{filter:none;opacity:1;box-shadow:0 18px 50px color-mix(in srgb,var(--stage) 30%, transparent);transform:translateY(-2px);}

  .stage--1{--stage:var(--c1);}
  .stage--2{--stage:var(--c2);}
  .stage--3{--stage:var(--c3);}
  .stage--4{--stage:var(--c4);}

  /* ---------- 页脚 ---------- */
  .footer{border-top:1px solid var(--line);background:var(--bg-2);padding:64px 0 56px;margin-top:30px;}
  .footer__mark{font-family:var(--serif);font-size:1.8rem;font-weight:600;letter-spacing:.04em;color:var(--ink);margin:0 0 4px;}
  .footer__sub{font-family:var(--sans);font-size:.72rem;letter-spacing:.32em;text-transform:uppercase;color:var(--ink-faint);}
  .footer__legal{margin-top:26px;color:var(--ink-soft);font-family:var(--serif);font-size:.95rem;line-height:1.9;}
  .footer__legal a{color:var(--ink-soft);border-bottom:1px solid var(--line-strong);}
  .footer__copy{color:var(--ink-faint);font-family:var(--sans);font-size:.78rem;letter-spacing:.1em;margin-top:18px;}

  /* ---------- 入场动效 ---------- */
  [data-reveal]{opacity:0;transform:translateY(22px);transition:opacity .8s var(--ease),transform .8s var(--ease);}
  [data-reveal].is-in{opacity:1;transform:none;}

  /* ---------- 响应式 ---------- */
  @media (max-width:760px){
    .nav__menu{display:none;}
    .spine{left:22px;}
    .stage{grid-template-columns:54px 1fr;gap:20px;padding:44px 0;}
    .stage__no{font-size:1.6rem;}
    .stage__panel{aspect-ratio:4/3;}
    .hero{padding-bottom:50px;}
    .hero__scroll{display:none;}
  }

  @media (prefers-reduced-motion:reduce){
    html{scroll-behavior:auto;}
    [data-reveal]{opacity:1;transform:none;transition:none;}
    .stage__panel{filter:none;opacity:1;}
    .stage__dot{background:var(--stage);border-color:var(--stage);}
    .stage__no{color:var(--stage);}
  }