:root{
  --bg:#f4f4f4;
  --bg-2:#ffffff;
  --bg-3:#f1f1f1;
  --ink:#111111;
  --ink-2:#222222;
  --muted:#7a7a7a;
  --muted-2:#9c9c9c;
  --accent:#c9892f;
}
*{box-sizing:border-box;margin:0;padding:0}
body{font-family:"Noto Sans SC","PingFang SC","Microsoft YaHei",system-ui,sans-serif;background:var(--bg);color:var(--ink);line-height:1.7}
img{max-width:100%;display:block}
a{text-decoration:none;color:inherit}

.side-nav{position:fixed;left:0;top:0;bottom:0;width:240px;background:var(--bg-2);border-right:1px solid #e5e5e5;display:flex;flex-direction:column;justify-content:space-between;padding:24px 18px;z-index:10}
.side-nav__brand{display:flex;align-items:center;gap:10px;font-weight:700}
.side-nav__brand img{height:28px}
.side-nav__menu{display:grid;gap:10px;margin-top:20px}
.side-nav__menu a{color:var(--ink-2);padding:6px 8px;border-radius:8px;transition:.2s}
.side-nav__menu a.active{background:var(--bg-3);color:var(--ink)}
.side-nav__footer{display:grid;gap:10px}
.side-nav__cta{background:var(--ink);color:#fff;border:0;border-radius:8px;padding:8px 12px;cursor:pointer}
.side-nav__tag{font-size:12px;color:var(--muted)}

.side-toggle{display:none;position:fixed;left:14px;top:14px;z-index:20;border:1px solid #ddd;background:#fff;border-radius:8px;padding:6px 10px}

.canvas{margin-left:240px;min-height:100vh}
.canvas section{padding:120px 6%}
.section-head h2{font-size:26px}
.section-head p{color:var(--muted);margin-top:8px}

.cover{background:var(--bg-2);padding-top:80px;padding-bottom:120px}
.cover__media img{height:420px;object-fit:cover;border-radius:18px}
.cover__text{margin-top:28px;max-width:720px}
.cover__badge{font-size:12px;color:var(--muted);letter-spacing:1px}
.cover h1{font-size:38px;margin-top:8px}
.cover__sub{font-size:20px;color:var(--ink-2);margin-top:6px}
.cover p{color:var(--muted);margin-top:10px}
.cover__actions{display:flex;gap:10px;margin-top:18px}
.btn-main{background:#111;color:#fff;padding:12px 26px;border-radius:8px;border:0;transition:all .25s}
.btn-main:hover{background:#333}
.btn-light{border:1px solid #ddd;padding:12px 24px;border-radius:8px;background:transparent}

.about{background:var(--bg-3);display:grid;grid-template-columns:1.1fr .9fr;gap:30px;align-items:center}
.about__media{position:relative}
.about__media img{border-radius:18px;height:360px;object-fit:cover}
.about__stamp{position:absolute;right:-12px;bottom:-12px;width:60px;height:60px;border-radius:50%;background:var(--accent);color:#fff;display:grid;place-items:center;font-weight:700}
.eyebrow{font-size:12px;color:var(--muted-2)}

.versions{background:var(--bg-2)}
.versions__rail{display:grid;grid-template-columns:auto 1fr auto;gap:12px;align-items:center;margin-top:18px}
.rail-track{display:grid;grid-auto-flow:column;grid-auto-columns:200px;gap:12px;overflow:hidden}
.rail-item{background:var(--bg-2);border-radius:16px;border:1px solid #eee;padding:16px;display:grid;gap:10px;place-items:center;cursor:pointer;transition:all .3s ease}
.rail-item:hover{transform:translateY(-6px);box-shadow:0 12px 30px rgba(0,0,0,0.08)}
.rail-item img{width:26px;height:26px;object-fit:contain}
.card{background:#ffffff;border-radius:16px;border:1px solid #eee;transition:all .3s ease}
.card:hover{transform:translateY(-6px);box-shadow:0 12px 30px rgba(0,0,0,0.08)}
.rail-btn{width:36px;height:36px;border-radius:50%;border:1px solid #ddd;background:#fff}
.versions__action{margin-top:14px}

.steps{background:var(--bg-3)}
.steps__grid{display:grid;grid-template-columns:repeat(5,1fr);gap:18px;margin-top:18px}
.step{display:grid;gap:8px;text-align:center}
.step-icon{width:60px;height:60px;border-radius:50%;background:#eef0f2;border:1px solid #d7dbe0;display:flex;align-items:center;justify-content:center;margin:auto}
.step-icon img{width:28px;height:28px;object-fit:contain;filter:drop-shadow(0 1px 1px rgba(0,0,0,.25))}
.step p{color:var(--muted);font-size:13px}

.video{background:var(--bg-2)}
.video__panel{position:relative;height:320px;border-radius:20px;background:url('../picture/video-cover.png') center/cover no-repeat;display:grid;place-items:center;text-align:center;cursor:pointer;overflow:hidden}
.video__panel::after{content:"";position:absolute;inset:0;background:rgba(0,0,0,0.45)}
.video__panel > *{position:relative;z-index:1}
.play-btn{width:72px;height:72px;border-radius:50%;background:#fff;display:flex;align-items:center;justify-content:center;box-shadow:0 10px 30px rgba(0,0,0,0.2);cursor:pointer;transition:all .3s}
.play-btn:hover{transform:scale(1.1)}
.video__title{color:#fff;font-size:22px;margin-top:10px}
.video__sub{color:#f1f1f1;font-size:12px;margin-top:4px}

.gallery{background:var(--bg-3)}
.gallery__rail{display:grid;grid-template-columns:auto 1fr auto;gap:12px;align-items:center;margin-top:18px}
.rail-track img{height:420px;object-fit:cover;border-radius:14px;cursor:zoom-in}
.img-card{transition:all .3s}
.img-card:hover{transform:translateY(-8px)}

.news{background:var(--bg-2)}
.news__grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;margin-top:18px}
.news-card{border-radius:14px;overflow:hidden;border:1px solid #eee;transition:all .3s}
.news-card:hover{transform:translateY(-6px);box-shadow:0 12px 25px rgba(0,0,0,.08)}
.news__card{background:#fff}
.news__card img{height:180px;object-fit:cover}
.news__date{padding:10px 16px 0;color:var(--muted);font-size:12px}
.news__card h3{padding:0 16px}
.news__card p{padding:0 16px 8px;color:var(--muted)}
.news__card button{margin:0 16px 16px}

.materials{background:var(--bg-3)}
.tabs{margin-top:18px}
.tabs__nav{display:flex;gap:10px}
.tab{border:1px solid #ddd;background:#fff;border-radius:999px;padding:6px 12px;cursor:pointer}
.tab.active{background:var(--ink);color:#fff;border-color:transparent}
.tabs__content{margin-top:14px}
.tab-pane{display:none}
.tab-pane.active{display:grid;gap:10px}
.doc{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;align-items:center;background:#fff;border:1px solid #eee;border-radius:10px;padding:10px 12px}
.doc span{color:var(--muted);font-size:12px}
.doc button{background:var(--accent);color:#fff;border:0;border-radius:8px;padding:6px 10px}
.faq-inline{margin-top:18px;background:#fff;border:1px solid #eee;border-radius:12px;padding:12px}
.faq-inline p{color:var(--muted);font-size:13px;margin-top:6px}

.contact{background:var(--bg-2);display:grid;grid-template-columns:1fr 1fr;gap:24px;align-items:center}
.contact__form{display:grid;gap:10px}
.contact__form input,.contact__form textarea{border:1px solid #ddd;border-radius:8px;padding:10px;background:#fff}

.footer{background:#fff;border-top:1px solid #e6e6e6}
.footer__grid{display:grid;grid-template-columns:repeat(5,1fr);gap:16px}
.footer h3{font-size:14px}
.footer a,.footer span,.footer p{display:block;color:var(--muted);font-size:12px;margin-top:6px}

.modal{position:fixed;inset:0;background:rgba(0,0,0,0.55);display:none;align-items:center;justify-content:center;z-index:9999;padding:20px}
.modal.open{display:flex}
.modal__card{background:#fff;border-radius:16px;padding:18px;max-width:520px;width:100%;display:grid;gap:10px;position:relative}
.modal__close{position:absolute;right:10px;top:8px;border:0;background:transparent;font-size:22px;cursor:pointer}
.modal__video video{width:100%;border-radius:12px}

.backtop{position:fixed;right:18px;bottom:18px;width:40px;height:40px;border-radius:50%;border:1px solid #ddd;background:#fff;display:none}

.icon-box{width:56px;height:56px;background:#eef0f2;border-radius:14px;border:1px solid #d7dbe0;display:flex;align-items:center;justify-content:center;margin:auto}
.icon-box img{width:26px;height:26px;object-fit:contain;filter:drop-shadow(0 1px 1px rgba(0,0,0,.25))}
.icon-box svg{width:26px;height:26px;fill:#111}

.fade-up{opacity:0;transform:translateY(40px);transition:all .6s}
.fade-up.show{opacity:1;transform:none}

@media (max-width:980px){
  .side-nav{position:fixed;left:0;top:0;bottom:0;transform:translateX(-100%);transition:.2s;background:var(--bg-2)}
  .side-nav.open{transform:translateX(0)}
  .side-toggle{display:block}
  .canvas{margin-left:0}
  .about,.contact{grid-template-columns:1fr}
  .news__grid{grid-template-columns:1fr 1fr}
  .steps__grid{grid-template-columns:1fr 1fr}
  .footer__grid{grid-template-columns:1fr 1fr}
}
@media (max-width:768px){
  .rail-btn{display:none}
  .rail-track{overflow-x:auto}
  .news__grid{grid-template-columns:1fr}
}