/* 必燃 AI 内容实验室 —— 暗色高级感主题 */
*{margin:0;padding:0;box-sizing:border-box}
:root{
  --bg:#0a0a0a;
  --bg-elev:#121212;
  --bg-card:#171717;
  --text:#fff;
  --muted:#8a8a8a;
  --muted-2:#555;
  --line:#262626;
  --accent:#fff;
}
html{scroll-behavior:smooth}
html,body{font-family:-apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",sans-serif;background:var(--bg);color:var(--text);line-height:1.6;-webkit-text-size-adjust:100%;overflow-x:hidden}
a{color:inherit;text-decoration:none}
img{max-width:100%;display:block}
.container{max-width:1280px;margin:0 auto;padding:0 32px}
::selection{background:#fff;color:#000}

/* ===== 顶部导航 ===== */
.nav{position:fixed;top:0;left:0;right:0;z-index:100;padding:18px 0;background:transparent;transition:background .3s,padding .3s,border-color .3s;border-bottom:1px solid transparent}
.nav.scrolled{background:rgba(10,10,10,.85);backdrop-filter:blur(14px);-webkit-backdrop-filter:blur(14px);padding:12px 0;border-bottom-color:rgba(255,255,255,.06)}
.nav-inner{display:flex;align-items:center;justify-content:space-between;gap:24px}
.logo{display:flex;align-items:flex-end;gap:6px;color:#fff}
.logo-zh{font-size:22px;font-weight:700;letter-spacing:1px;line-height:1}
.logo-r{font-size:9px;color:#888;margin:0 4px 2px 0;vertical-align:super}
.logo-en{font-size:12px;letter-spacing:3px;color:#999;font-weight:400;margin-bottom:2px}
.nav-logo-img{height:32px}

.nav-menu{display:flex;align-items:center;gap:36px;flex:1;justify-content:center}
.nav-menu .nav-item{position:relative;text-align:center;font-size:14px;cursor:pointer;color:#ddd;padding:6px 0;transition:color .2s}
.nav-menu .nav-item:hover{color:#fff}
.nav-menu .nav-item .zh{display:block;font-weight:500;font-size:14px}
.nav-menu .nav-item .en{display:block;font-size:10px;color:#666;letter-spacing:2px;margin-top:2px}
.nav-menu .nav-item.active::after{content:'';position:absolute;left:50%;bottom:-4px;width:18px;height:1px;background:#fff;transform:translateX(-50%)}

.nav-right{display:flex;align-items:center;gap:14px}
.nav-pill{display:inline-block;padding:9px 18px;border:1px solid rgba(255,255,255,.5);color:#fff;border-radius:30px;font-size:13px;transition:background .2s,color .2s}
.nav-pill:hover{background:#fff;color:#000}
.nav-burger{width:38px;height:38px;border:1px solid rgba(255,255,255,.4);border-radius:50%;display:flex;align-items:center;justify-content:center;background:transparent;color:#fff;cursor:pointer;transition:background .2s,color .2s}
.nav-burger:hover{background:#fff;color:#000}

/* 侧抽屉（汉堡菜单）*/
.drawer{position:fixed;top:0;right:-360px;width:340px;height:100vh;background:#0a0a0a;border-left:1px solid var(--line);z-index:200;transition:right .3s ease;padding:80px 40px 40px;display:flex;flex-direction:column;gap:18px}
.drawer.open{right:0}
.drawer a{color:#ccc;font-size:16px;padding:10px 0;border-bottom:1px solid var(--line);transition:color .2s}
.drawer a:hover{color:#fff}
.drawer .drawer-close{position:absolute;top:20px;right:24px;background:none;border:none;color:#fff;font-size:24px;cursor:pointer}
.drawer-mask{position:fixed;inset:0;background:rgba(0,0,0,.5);z-index:150;opacity:0;pointer-events:none;transition:opacity .3s}
.drawer-mask.show{opacity:1;pointer-events:auto}

/* ===== Hero ===== */
.hero{position:relative;min-height:100vh;background:#000 center/cover no-repeat;overflow:hidden;display:flex;align-items:center}
.hero::before{content:'';position:absolute;inset:0;background:linear-gradient(180deg,rgba(0,0,0,.4) 0%,rgba(0,0,0,.55) 60%,rgba(0,0,0,.9) 100%);z-index:1}
.hero-bg{position:absolute;inset:0;background:#000 center/cover no-repeat;background-image:linear-gradient(135deg,#0a0a0a 0%,#1a1a1a 40%,#0d1218 100%);animation:kenburns 18s ease-in-out infinite alternate}
@keyframes kenburns{0%{transform:scale(1) translate(0,0)}100%{transform:scale(1.08) translate(-1.5%,-1%)}}
.hero-inner{position:relative;z-index:2;padding:140px 32px 100px;width:100%}
.hero-tag-zh{font-size:48px;font-weight:300;letter-spacing:4px;margin-bottom:8px;opacity:0;animation:fadeUp .9s .2s forwards}
.hero-title{font-size:60px;font-weight:300;letter-spacing:4px;line-height:1.15;max-width:880px;opacity:0;animation:fadeUp .9s .4s forwards}
.hero-sub{font-size:18px;color:#ddd;margin-top:30px;letter-spacing:1px;max-width:720px;opacity:0;animation:fadeUp .9s .6s forwards}
.hero-en{font-size:12px;color:#777;letter-spacing:4px;margin-top:8px;opacity:0;animation:fadeUp .9s .7s forwards}
.hero-actions{display:flex;align-items:center;gap:12px;margin-top:48px;opacity:0;animation:fadeUp .9s .9s forwards}
.hero-cta{display:inline-flex;align-items:center;gap:12px;padding:14px 24px 14px 14px;border:1px solid rgba(255,255,255,.35);border-radius:60px;color:#fff;font-size:14px;transition:background .2s,color .2s,border-color .2s}
.hero-cta.primary{background:#fff;color:#000;border-color:#fff}
.hero-cta.secondary{padding-left:24px;background:rgba(0,0,0,.18);backdrop-filter:blur(8px)}
.hero-cta:hover{background:#fff;color:#000;border-color:#fff}
.hero-cta .play-circle{width:38px;height:38px;border:1px solid currentColor;border-radius:50%;display:flex;align-items:center;justify-content:center;font-size:12px}

@keyframes fadeUp{from{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}

/* 侧栏 01-04 + SCROLL DOWN */
.hero-rail{position:absolute;top:50%;right:32px;transform:translateY(-50%);z-index:3;display:flex;flex-direction:column;gap:18px;color:#666;font-size:11px;letter-spacing:3px}
.hero-rail .num{padding:4px 0;cursor:pointer;transition:color .2s}
.hero-rail .num.active{color:#fff}
.hero-rail .num.active::before{content:'';display:inline-block;width:18px;height:1px;background:#fff;margin-right:8px;vertical-align:middle}
.hero-side-num{position:absolute;left:32px;top:50%;transform:translateY(-50%);z-index:3;color:#444;font-size:11px;letter-spacing:3px;writing-mode:vertical-rl;text-orientation:mixed}
.scroll-down{position:absolute;right:32px;bottom:32px;z-index:3;color:#999;font-size:10px;letter-spacing:3px;display:flex;flex-direction:column;align-items:center;gap:10px}
.scroll-down::after{content:'';width:1px;height:40px;background:linear-gradient(180deg,#999,transparent);animation:scrollLine 2s ease-in-out infinite}
@keyframes scrollLine{0%{transform:scaleY(0);transform-origin:top}50%{transform:scaleY(1);transform-origin:top}50.001%{transform-origin:bottom}100%{transform:scaleY(0);transform-origin:bottom}}

/* ===== 服务卡片 ===== */
.services{padding:80px 0}
/* 默认：等大自适应网格（任意数量都规整，不会落单） */
.serv-grid{display:grid;gap:14px;grid-template-columns:repeat(auto-fit,minmax(300px,1fr))}
.serv-card{position:relative;background:#1b1b1d;border-radius:10px;overflow:hidden;min-height:300px;cursor:pointer;transition:transform .4s ease}
.serv-card .bg{position:absolute;inset:0;background:center/cover no-repeat;transform:scale(1.07);transition:transform .8s ease;z-index:1}
.serv-card::after{content:'';position:absolute;inset:0;background:transparent;z-index:2}
.serv-card .content{position:absolute;inset:0;z-index:3;padding:32px;display:flex;flex-direction:column;justify-content:flex-end}
.serv-card .content{text-shadow:0 1px 12px rgba(0,0,0,.75),0 1px 3px rgba(0,0,0,.6)}
.serv-card .en{color:#fff;font-size:13px;letter-spacing:3px;opacity:.85;margin-bottom:6px}
.serv-card .zh{color:#fff;font-size:24px;font-weight:500;letter-spacing:2px}
.serv-card .desc{color:#eee;font-size:13px;margin-top:14px;line-height:1.7;max-width:80%}
.serv-card .more{color:#ddd;font-size:12px;margin-top:18px;letter-spacing:2px;opacity:0;transform:translateY(8px);transition:opacity .3s,transform .3s}
.serv-card:hover .bg{transform:scale(1.13)}
.serv-card:hover .more{opacity:1;transform:translateY(0)}
.serv-card:hover .more::after{content:' →';color:#fff}

/* 文字颜色随底图自适应：深色底图保持默认白字；浅色底图改深字+浅蒙层 */
.serv-card.text-dark .content{text-shadow:0 1px 12px rgba(255,255,255,.7),0 1px 3px rgba(255,255,255,.6)}
.serv-card.text-dark .en{color:#222;opacity:.75}
.serv-card.text-dark .zh{color:#000}
.serv-card.text-dark .desc{color:#333}
.serv-card.text-dark .more{color:#333}
.serv-card.text-dark:hover .more::after{color:#000}
.serv-card[href]{cursor:pointer}

/* 恰好 4 张：bento 不对称布局（左大卡 + 右上宽卡 + 右下两张并排） */
.serv-grid.bento4{grid-template-columns:repeat(4,1fr);grid-template-rows:repeat(2,minmax(230px,1fr))}
.serv-grid.bento4 .serv-card{min-height:0}
.serv-grid.bento4 .serv-card:nth-child(1){grid-column:1/3;grid-row:1/3}
.serv-grid.bento4 .serv-card:nth-child(2){grid-column:3/5;grid-row:1/2}
.serv-grid.bento4 .serv-card:nth-child(3){grid-column:3/4;grid-row:2/3}
.serv-grid.bento4 .serv-card:nth-child(4){grid-column:4/5;grid-row:2/3}

/* ===== Lab 区 ===== */
.lab{padding:30px 0 80px}
.lab-card{position:relative;border-radius:8px;overflow:hidden;min-height:300px;background:#171717}
.lab-card .bg{position:absolute;inset:0;background:center/cover no-repeat;background-image:linear-gradient(120deg,#1a1f2a,#0a0d12);z-index:1}
.lab-card::after{content:'';position:absolute;inset:0;background:linear-gradient(90deg,rgba(0,0,0,.85) 0%,rgba(0,0,0,.45) 50%,rgba(0,0,0,.6) 100%);z-index:2}
.lab-card .content{position:relative;z-index:3;padding:50px}
.lab-card .en{color:#fff;font-size:13px;letter-spacing:3px;opacity:.8;margin-bottom:6px}
.lab-card .zh{font-size:30px;font-weight:500;letter-spacing:2px}
.lab-card .desc{color:#bbb;font-size:14px;margin-top:20px;max-width:50%;white-space:pre-line}
.lab-card .more{display:inline-block;color:#fff;font-size:12px;margin-top:30px;letter-spacing:2px;padding:10px 20px;border:1px solid rgba(255,255,255,.3);border-radius:30px;transition:background .2s,color .2s}
.lab-card .more:hover{background:#fff;color:#000}

/* ===== 技术 + 关于 ===== */
.tech-about{padding:30px 0 80px;display:grid;grid-template-columns:1.7fr 1fr;gap:14px}
.tech-block{background:var(--bg-card);border-radius:8px;padding:36px}
.tech-block .label-en{color:#888;font-size:11px;letter-spacing:3px}
.tech-block .label-zh{font-size:18px;margin-top:6px;letter-spacing:1px}
.block-intro{color:#888;font-size:13px;line-height:1.8;max-width:680px;margin-top:14px}
.tech-list{display:flex;align-items:center;gap:36px;margin-top:30px;flex-wrap:wrap}
.tech-item{color:#bbb;font-size:14px;font-weight:500;opacity:.7;transition:opacity .2s}
.tech-item:hover{opacity:1;color:#fff}
.about-block{background:var(--bg-card);border-radius:8px;padding:36px;background:linear-gradient(135deg,#1a1a1a 0%,#0e0e0e 100%);position:relative;overflow:hidden}
.about-block .bg{position:absolute;inset:0;background:center/cover no-repeat;opacity:.25}
.about-block > *{position:relative;z-index:1}
.about-block .label-en{color:#888;font-size:11px;letter-spacing:3px}
.about-block .label-zh{font-size:22px;margin-top:6px;letter-spacing:1px}
.about-block .desc{color:#aaa;font-size:13px;margin-top:18px;line-height:1.8;white-space:pre-line}
.about-block .more{display:inline-flex;align-items:center;gap:10px;margin-top:24px;padding:10px 18px;border:1px solid rgba(255,255,255,.3);border-radius:30px;font-size:12px;letter-spacing:2px;transition:background .2s,color .2s}
.about-block .more:hover{background:#fff;color:#000}

/* ===== 案例 ===== */
.cases-sec{padding:30px 0 80px}
.sec-head{display:flex;justify-content:space-between;align-items:flex-end;margin-bottom:24px}
.sec-head .label-en{color:#888;font-size:11px;letter-spacing:3px}
.sec-head .label-zh{font-size:24px;margin-top:6px;letter-spacing:1px}
.sec-head a{color:#888;font-size:12px;letter-spacing:2px;padding:8px 16px;border:1px solid rgba(255,255,255,.15);border-radius:30px;transition:all .2s}
.sec-head a:hover{background:#fff;color:#000}
.case-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:14px}
.case-card{position:relative;background:var(--bg-card);border-radius:8px;overflow:hidden;aspect-ratio:4/3;display:block}
.case-card .bg{position:absolute;inset:0;background:center/cover no-repeat;background-image:linear-gradient(135deg,#222,#0a0a0a);transition:transform .6s}
.case-card::after{content:'';position:absolute;inset:0;background:linear-gradient(180deg,rgba(0,0,0,0) 50%,rgba(0,0,0,.9) 100%);z-index:1}
.case-card .info{position:absolute;left:0;right:0;bottom:0;padding:18px;z-index:2}
.case-card .info .t{font-size:15px;font-weight:500}
.case-card .info .s{color:#888;font-size:11px;letter-spacing:1px;margin-top:4px}
.case-card:hover .bg{transform:scale(1.06)}

/* ===== 合作优势 ===== */
.value-sec{padding:30px 0 80px}
.value-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}
.value-card{position:relative;min-height:220px;padding:30px;background:var(--bg-card);border:1px solid transparent;border-radius:8px;transition:border-color .25s,transform .25s}
.value-card:hover{border-color:#3a3a3a;transform:translateY(-3px)}
.value-num{color:#555;font-size:11px;letter-spacing:3px}
.value-card h3{font-size:20px;font-weight:500;letter-spacing:1px;margin-top:42px}
.value-card p{color:#8e8e8e;font-size:13px;line-height:1.9;margin-top:14px}

/* ===== 合作流程 ===== */
.process-sec{padding:30px 0 80px}
.sec-note{color:#666;font-size:12px;letter-spacing:1px}
.process-list{list-style:none;display:grid;grid-template-columns:repeat(4,1fr);border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.process-list li{min-height:190px;padding:28px 24px;border-right:1px solid var(--line)}
.process-list li:last-child{border-right:none}
.process-list li>span{color:#555;font-size:11px;letter-spacing:3px}
.process-list strong{display:block;font-size:18px;font-weight:500;margin-top:34px}
.process-list p{color:#777;font-size:12px;line-height:1.8;margin-top:12px}

/* ===== 新闻 ===== */
.news-sec{padding:30px 0 80px}
.news-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:14px}
.news-card{display:block;background:var(--bg-card);border-radius:8px;overflow:hidden;transition:transform .35s,background .35s}
.news-card:hover{transform:translateY(-4px);background:#191919}
.news-card .bg{aspect-ratio:16/10;background:#222 center/cover no-repeat;background-image:linear-gradient(135deg,#1a1a1a,#0a0a0a)}
.news-card .body{padding:18px}
.news-card .date{color:#666;font-size:11px;letter-spacing:1px}
.news-card .t{margin-top:8px;font-size:14px;font-weight:500}
.news-card .d{margin-top:8px;color:#888;font-size:12px;line-height:1.6;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}

/* ===== 联系 ===== */
.contact-sec{padding:30px 0 80px}
.contact-grid{display:grid;grid-template-columns:1fr 1fr;gap:32px;background:var(--bg-card);border-radius:8px;padding:48px}
.contact-grid .label-en{color:#888;font-size:11px;letter-spacing:3px}
.contact-grid .label-zh{font-size:26px;margin-top:6px}
.contact-lead{color:#888;font-size:13px;line-height:1.8;max-width:520px;margin-top:14px}
.contact-list{margin-top:24px;display:flex;flex-direction:column;gap:14px}
.contact-list .it{color:#ccc;font-size:14px;display:flex;gap:14px;align-items:flex-start;white-space:pre-line}
.contact-list .it .k{color:#666;font-size:12px;letter-spacing:2px;min-width:70px}
.contact-list a:hover{color:#fff;text-decoration:underline}
.contact-actions{display:flex;gap:10px;flex-wrap:wrap;margin-top:28px}
.contact-btn{appearance:none;border:1px solid #3b3b3b;background:transparent;color:#ddd;border-radius:30px;padding:11px 18px;font:inherit;font-size:12px;cursor:pointer;transition:background .2s,color .2s,border-color .2s}
.contact-btn.primary,.contact-btn:hover{background:#fff;color:#000;border-color:#fff}
.brief-card{background:#101010;border:1px solid var(--line);border-radius:8px;min-height:260px;padding:34px}
.brief-tag{color:#666;font-size:10px;letter-spacing:3px}
.brief-card h3{font-size:20px;font-weight:500;margin-top:14px}
.brief-card ul{list-style:none;margin-top:24px;display:grid;grid-template-columns:1fr 1fr;gap:12px}
.brief-card li{color:#aaa;font-size:13px;padding-left:16px;position:relative}
.brief-card li::before{content:'·';position:absolute;left:0;color:#fff}
.brief-card>p{color:#666;font-size:12px;margin-top:28px}

/* ===== Footer ===== */
.footer{background:#070707;color:#888;border-top:1px solid var(--line);padding:60px 0 24px}
.footer a{color:#888;transition:color .2s}
.footer a:hover{color:#fff}
.footer-top{display:grid;grid-template-columns:2fr 1fr 1fr 1.4fr;gap:40px;padding-bottom:40px;border-bottom:1px solid var(--line)}
.footer-brand .desc{color:#777;font-size:12px;margin-top:14px;line-height:1.8;white-space:pre-line}
.footer-col h4{color:#fff;font-size:13px;margin-bottom:14px;font-weight:500;letter-spacing:2px}
.footer-col ul{list-style:none;display:flex;flex-direction:column;gap:8px;font-size:12px;color:#888}
.footer-bottom{margin-top:24px;display:flex;justify-content:space-between;color:#555;font-size:12px;flex-wrap:wrap;gap:10px}

/* ===== Scroll Reveal 动效 ===== */
.reveal{opacity:0;transform:translateY(30px);transition:opacity .9s ease, transform .9s ease}
.reveal.on{opacity:1;transform:none}

/* ===== 响应式 ===== */
@media (max-width:980px){
  .nav-menu{display:none}
  .hero-tag-zh{font-size:32px}
  .hero-title{font-size:36px;letter-spacing:3px}
  .hero-sub{font-size:14px}
  .hero-rail,.hero-side-num{display:none}
  .scroll-down{display:none}
  .serv-grid,.serv-grid.bento4{grid-template-columns:1fr;grid-template-rows:none}
  .serv-grid.bento4 .serv-card{grid-column:auto!important;grid-row:auto!important;min-height:280px}
  .tech-about{grid-template-columns:1fr}
  .lab-card .desc{max-width:100%}
  .lab-card .content{padding:30px}
  .news-grid{grid-template-columns:repeat(2,1fr)}
  .value-grid{grid-template-columns:1fr}
  .process-list{grid-template-columns:1fr 1fr}
  .process-list li:nth-child(2){border-right:none}
  .process-list li:nth-child(-n+2){border-bottom:1px solid var(--line)}
  .contact-grid{grid-template-columns:1fr;padding:28px}
  .footer-top{grid-template-columns:1fr 1fr;gap:24px}
  .footer-brand{grid-column:1/-1}
}
@media (max-width:560px){
  .container{padding:0 20px}
  .hero{min-height:92svh}
  .hero::before{background:linear-gradient(180deg,rgba(0,0,0,.42),rgba(0,0,0,.48) 55%,rgba(0,0,0,.82))}
  .hero-bg{filter:brightness(1.16)}
  .hero-inner{padding:120px 20px 72px}
  .hero-tag-zh{font-size:26px}
  .hero-title{font-size:31px;line-height:1.28;letter-spacing:.5px}
  .hero-sub{font-size:14px;line-height:1.8;margin-top:20px}
  .hero-en{font-size:10px;line-height:1.8;letter-spacing:2px}
  .hero-actions{align-items:stretch;flex-direction:column;gap:10px;margin-top:32px;max-width:210px}
  .hero-cta{justify-content:center;padding:11px 18px}
  .hero-cta.secondary{padding-left:18px}
  .news-grid{grid-template-columns:1fr}
  .process-list{grid-template-columns:1fr}
  .process-list li{border-right:none;border-bottom:1px solid var(--line)}
  .process-list li:last-child{border-bottom:none}
  .sec-note{display:none}
  .brief-card ul{grid-template-columns:1fr}
  .contact-actions{display:grid;grid-template-columns:1fr 1fr}
  .contact-actions .primary{grid-column:1/-1}
}