/* AI LINE · V2 极简亮色（Apple 式） */
:root{
  --bg:#fff; --bg2:#f5f5f7; --card:#fff; --card-gray:#f5f5f7;
  --text:#1d1d1f; --text2:#6e6e73; --hair:#d2d2d7; --blue:#0071e3;
  --nav-h:52px; --radius:18px;
  --sans:-apple-system,"SF Pro Display","SF Pro SC","PingFang SC","Microsoft YaHei","Segoe UI",sans-serif;
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-font-smoothing:antialiased}
body{background:var(--bg);color:var(--text);font-family:var(--sans);line-height:1.6;overflow-x:hidden}
img{display:block;width:100%}
a{color:inherit;text-decoration:none}
.en{font-family:"SF Pro Display",-apple-system,Arial,sans-serif}
h1,h2{font-weight:650;letter-spacing:-.018em;line-height:1.12}
section{scroll-margin-top:calc(var(--nav-h) + 10px)}
.wrap{max-width:1040px;margin:0 auto;padding:0 22px}

/* ---------- nav ---------- */
nav{position:fixed;top:0;left:0;right:0;height:var(--nav-h);z-index:100;
  background:rgba(255,255,255,.72);backdrop-filter:saturate(180%) blur(20px);-webkit-backdrop-filter:saturate(180%) blur(20px);
  border-bottom:1px solid transparent;transition:border-color .3s}
nav.solid{border-bottom-color:var(--hair)}
.nav-inner{max-width:1040px;margin:0 auto;height:100%;display:flex;align-items:center;justify-content:space-between;padding:0 22px}
.logo{font-size:15px;font-weight:700;letter-spacing:.02em;display:flex;align-items:center;gap:9px}
.logo-img{width:27px;height:27px;border-radius:8px;display:block;flex:none}
.logo span{font-weight:400;color:var(--text2)}
.nav-links{display:flex;align-items:baseline;gap:28px}
.nav-links a{font-size:12.5px;color:rgba(29,29,31,.78);transition:color .2s}
.nav-links a:hover{color:var(--text)}
/* 「服务」下拉：桌面悬浮/点击开合，手机端并入汉堡列表静态展开 */
.nav-drop{position:relative}
.drop-btn{display:inline-flex;align-items:center;gap:6px;background:none;border:0;padding:0;font-family:inherit;font-size:12.5px;line-height:inherit;color:rgba(29,29,31,.78);cursor:pointer;transition:color .2s}
.drop-btn:hover,.nav-drop.open .drop-btn{color:var(--text)}
.caret{width:0;height:0;border-left:3.5px solid transparent;border-right:3.5px solid transparent;border-top:4px solid currentColor;transition:transform .25s}
.nav-drop.open .caret{transform:rotate(180deg)}
.drop-menu a{display:block;padding:9px 14px;border-radius:9px;font-size:13px;color:var(--text);white-space:nowrap}
.drop-menu a:hover{background:var(--bg2);color:var(--text)}
@media(min-width:861px){
  .drop-menu{position:absolute;top:calc(100% + 12px);left:50%;transform:translate(-50%,8px);min-width:136px;padding:6px;
    background:#fff;border:1px solid var(--hair);border-radius:14px;box-shadow:0 14px 34px rgba(0,0,0,.10);
    opacity:0;visibility:hidden;transition:.22s}
  .drop-menu::before{content:"";position:absolute;left:0;right:0;top:-14px;height:14px}   /* 悬停桥：跨过按钮与菜单间的空隙 */
  .nav-drop:hover .drop-menu,.nav-drop.open .drop-menu{opacity:1;visibility:visible;transform:translate(-50%,0)}
}
@media(max-width:860px){
  .nav-links{display:none}
  nav.open .nav-links{display:flex;position:absolute;top:var(--nav-h);left:0;right:0;flex-direction:column;gap:0;
    background:rgba(255,255,255,.97);border-bottom:1px solid var(--hair);padding:8px 22px 16px}
  nav.open .nav-links a{padding:11px 0;border-bottom:1px solid #ececed;font-size:15px}
  nav.open .nav-drop{border-bottom:1px solid #ececed}
  nav.open .drop-btn{width:100%;padding:11px 0;font-size:15px;justify-content:flex-start}
  nav.open .caret{display:none}
  nav.open .drop-menu{position:static;transform:none;min-width:0;padding:0 0 4px;border:0;box-shadow:none;background:none;opacity:1;visibility:visible}
  nav.open .drop-menu a{padding:10px 0 10px 14px;font-size:14.5px;color:rgba(29,29,31,.78);border:0}
}
.burger{display:none;width:36px;height:36px;border:0;background:none;cursor:pointer;position:relative}
.burger span{position:absolute;left:8px;right:8px;height:1.5px;background:var(--text);transition:.3s}
.burger span:nth-child(1){top:14px}.burger span:nth-child(2){top:21px}
nav.open .burger span:nth-child(1){top:17px;transform:rotate(45deg)}
nav.open .burger span:nth-child(2){top:17px;transform:rotate(-45deg)}
@media(max-width:860px){.burger{display:block}}

/* ---------- hero：100svh 片头字幕卡 ---------- */
.hero{position:relative;min-height:100vh;min-height:100svh;display:flex;flex-direction:column;
  padding:var(--nav-h) 22px 0;overflow:hidden}
.hero-fx{position:absolute;inset:0;pointer-events:none}
.blob{position:absolute;border-radius:50%;filter:blur(90px)}
.blob.b1{width:56vw;height:56vw;max-width:820px;max-height:820px;left:-12%;top:-18%;
  background:radial-gradient(closest-side,rgba(126,178,255,.4),rgba(126,178,255,0));animation:drift1 16s ease-in-out infinite alternate}
.blob.b2{width:46vw;height:46vw;max-width:680px;max-height:680px;right:-10%;bottom:-6%;
  background:radial-gradient(closest-side,rgba(255,196,120,.34),rgba(255,196,120,0));animation:drift2 20s ease-in-out infinite alternate}
@keyframes drift1{to{transform:translate(9vw,7vh) scale(1.12)}}
@keyframes drift2{to{transform:translate(-7vw,-6vh) scale(.92)}}
.wm{position:absolute;right:-1.5%;bottom:-4%;font-size:clamp(120px,23vw,330px);font-weight:800;
  letter-spacing:-.05em;line-height:.78;white-space:nowrap;color:transparent;
  -webkit-text-stroke:1.5px rgba(29,29,31,.06);user-select:none}
.corner{position:absolute;top:calc(var(--nav-h) + 20px);font-size:10.5px;letter-spacing:.24em;color:var(--text2)}
.corner.tl{left:24px}
.corner.tr{right:24px}
.hero-main{position:relative;flex:1;display:flex;flex-direction:column;justify-content:center;width:100%;max-width:1160px;margin:0 auto}
.hero-copy{text-align:left}
.eyebrow{font-size:13.5px;color:var(--text2);margin-bottom:20px;letter-spacing:.04em}
.eyebrow .dot{display:inline-block;width:8px;height:8px;border-radius:50%;background:var(--blue);
  margin-right:10px;vertical-align:1px;animation:pulse 2.4s ease-in-out infinite}
@keyframes pulse{0%,100%{opacity:1;transform:scale(1)}50%{opacity:.45;transform:scale(.78)}}
.hero h1{font-size:clamp(42px,7.2vw,94px);margin:0;line-height:1.07;letter-spacing:-.025em}
.hero h1 em{font-style:normal;color:var(--blue)}
.sub{font-size:clamp(15px,1.6vw,18px);color:var(--text2);margin-top:22px;max-width:640px;line-height:1.8}
.links{display:flex;gap:14px;margin-top:34px;flex-wrap:wrap}
.pill{display:inline-flex;align-items:center;gap:8px;padding:14px 30px;border-radius:999px;
  background:var(--text);color:#fff;font-weight:600;font-size:15.5px;text-decoration:none;
  transition:transform .25s,box-shadow .25s}
.pill:hover{transform:translateY(-2px);box-shadow:0 16px 32px -14px rgba(0,0,0,.45)}
.pill.ghost{background:rgba(255,255,255,.7);color:var(--text);border:1px solid var(--hair)}
.pill.ghost:hover{border-color:var(--blue);color:var(--blue);box-shadow:none}
.chev{margin-left:2px}
.hero-strip{position:relative;border-top:1px solid var(--hair);width:100%;max-width:1160px;margin:0 auto;
  padding:22px 0 26px;display:flex;align-items:center;gap:clamp(20px,4.5vw,60px);flex-wrap:wrap}
.hs-item+.hs-item{border-left:1px solid var(--hair);padding-left:clamp(20px,4.5vw,60px)}
.hs-item b{display:block;font-size:clamp(24px,2.8vw,38px);font-weight:700;letter-spacing:-.02em}
.hs-item[hidden]{display:none}
.hs-item span{font-size:12.5px;color:var(--text2)}
.scroll-cue{margin-left:auto;display:flex;align-items:center;gap:12px;font-size:10.5px;
  letter-spacing:.26em;color:var(--text2);text-decoration:none}
.scroll-cue i{width:1px;height:36px;background:linear-gradient(var(--text),transparent);display:block;
  animation:cue 1.9s ease-in-out infinite;transform-origin:top}
@keyframes cue{0%,100%{transform:scaleY(.35);opacity:.4}50%{transform:scaleY(1);opacity:1}}
@media(max-width:820px){
  .corner{display:none}
  .hero-strip{display:grid;grid-template-columns:repeat(3,1fr);gap:20px 12px;padding:18px 0 22px}
  .hs-item+.hs-item{border-left:none;padding-left:0}
  .scroll-cue{display:none}
}
@media (prefers-reduced-motion:reduce){.blob,.eyebrow .dot,.scroll-cue i{animation:none}}

/* ---------- mentors ---------- */
.mentors{padding:110px 0 96px}
.mentors h2{font-size:clamp(30px,4.4vw,48px);text-align:center;margin-bottom:52px}
.mentor-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}
@media(max-width:860px){.mentor-grid{grid-template-columns:repeat(2,1fr)}}
@media(max-width:560px){.mentor-grid{grid-template-columns:1fr}}
.mentor{background:var(--bg2);border-radius:var(--radius);padding:24px;display:flex;gap:15px;align-items:center;
  transition:transform .35s cubic-bezier(.2,.7,.3,1.2),box-shadow .35s;cursor:default}
.mentor:hover{transform:translateY(-4px);box-shadow:0 16px 34px -18px rgba(0,0,0,.25)}
.avatar{width:48px;height:48px;border-radius:50%;flex:none;display:grid;place-items:center;color:#fff;font-weight:700;font-size:18px;
  background:linear-gradient(135deg,#5e8bff,#0071e3)}
.mentor b{display:block;font-size:16px;font-weight:650}
.mentor span{font-size:12.5px;color:var(--text2)}

/* ---------- authors ---------- */
/* 每位讲师占满一整屏；吸附落位=区块顶边贴住视口顶，下一节完全不可见 */
.author{min-height:100vh;min-height:100svh;display:flex;flex-direction:column;
  padding:calc(var(--nav-h) + 14px) 0 48px;scroll-margin-top:0}
/* 头部锚定顶部，简介紧随其后组成"信息组"；轮播用 auto 边距在剩余空间垂直居中 */
/* wrap 不再撑满剩余高度——那是空隙全堆中段、页面松散的根源 */
/* width:100% 必须显式给：flex 列里左右 auto 边距会取消默认拉伸，导致 wrap 缩成内容宽 */
.author .wrap{width:100%;max-width:1160px;padding:12px 22px 0}
.author .a-head{margin-bottom:40px}
.author .strip.cf{margin:auto 0}
.author.gray{background:var(--bg2)}
.a-head{display:flex;gap:22px;align-items:flex-start;margin-bottom:40px}
.a-no{font-size:clamp(40px,5vw,60px);font-weight:700;line-height:1;color:var(--hair);
  -webkit-text-stroke:0;letter-spacing:-.02em;min-width:66px}
.a-title h2{font-size:clamp(26px,3.4vw,38px)}
.a-title p{font-size:13.5px;color:var(--text2);margin-top:8px;max-width:640px}
.a-title .award-line{color:#8a6a00;background:#fff7e0;border-radius:99px;display:inline-block;padding:5px 14px;margin-top:12px;font-size:12.5px}
.author.gray .a-title .award-line{background:#fff}
.a-body{display:grid;grid-template-columns:280px 1fr;gap:36px;align-items:start}
@media(max-width:900px){.a-body{grid-template-columns:1fr}}
.a-bio p{font-size:14.5px;color:var(--text2);margin-bottom:12px}
.a-bio b{color:var(--text);font-weight:600}
.a-bio blockquote{border-left:2px solid var(--blue);padding:2px 0 2px 14px;font-size:13.5px;color:var(--text);margin-top:18px}
.works{display:flex;align-items:center;gap:20px;overflow-x:auto;scroll-snap-type:x proximity;padding:6px max(22px,calc((100% - 996px)/2)) 10px;scroll-padding-inline:max(22px,calc((100% - 996px)/2));scrollbar-width:none}
.work{border-radius:var(--radius);overflow:hidden;background:var(--card);cursor:zoom-in;
  box-shadow:0 1px 2px rgba(0,0,0,.05);transition:transform .4s cubic-bezier(.2,.7,.3,1),box-shadow .4s}
.author.white .work{background:var(--card-gray)}
.work:hover{transform:translateY(-5px);box-shadow:0 22px 44px -20px rgba(0,0,0,.3)}
.work .media{overflow:hidden}
.work img{aspect-ratio:16/9;object-fit:cover;transition:transform .8s cubic-bezier(.2,.7,.25,1)}
.work.tall{grid-row:span 2}
.work.tall img{aspect-ratio:9/13.4}
.work:hover img{transform:scale(1.045)}
.work figcaption{padding:15px 18px 17px}
.work figcaption b{display:block;font-size:16px;font-weight:650}
.work figcaption span{font-size:12.5px;color:var(--text2)}

/* ---------- awards ---------- */
.awards{background:#000;color:#f5f5f7;padding:100px 0}
.awards h2{font-size:clamp(30px,4.4vw,48px);text-align:center;margin-bottom:56px}
.award-list{display:grid;gap:14px;max-width:760px;margin:0 auto}
.award{background:#161617;border-radius:var(--radius);padding:26px 28px;display:flex;gap:24px;align-items:flex-start}
.award .year{font-size:15px;color:#86868b;font-weight:600;padding-top:3px}
.award b{display:block;font-size:17px;font-weight:650;margin-bottom:4px}
.award span{font-size:13px;color:#a1a1a6}

/* ---------- services（服务内容：编号清单，与 Q&A 同一套亮色排版语言） ---------- */
.services{padding:96px 0;background:var(--bg)}
.services h2{font-size:clamp(26px,3.4vw,38px);margin-bottom:38px}
.svc-list{max-width:840px}
.svc{display:flex;gap:26px;align-items:flex-start;padding:24px 4px;border-bottom:1px solid var(--hair)}
.svc:first-child{border-top:1px solid var(--hair)}
.svc .no{flex:none;font-size:14px;font-weight:600;color:var(--blue);letter-spacing:.06em;padding-top:3px}
.svc b{display:block;font-size:17px;font-weight:650;margin-bottom:4px;transition:color .25s}
.svc span{font-size:13.5px;color:var(--text2);line-height:1.6}
.svc:hover b{color:var(--blue)}
@media(max-width:640px){.svc{gap:16px;padding:20px 2px}.svc b{font-size:15.5px}}

/* ---------- footer ---------- */
footer{background:var(--bg2);padding:56px 0 40px;text-align:center}
.slogan{font-size:clamp(16px,2.2vw,20px);font-weight:600;letter-spacing:.01em}
.meta{font-size:13px;color:var(--text2);margin-top:10px}
.legal{font-size:11.5px;color:#a1a1a6;margin-top:26px;letter-spacing:.08em;text-transform:uppercase}

/* ---------- lightbox ---------- */
.lb{position:fixed;inset:0;z-index:200;display:none;align-items:center;justify-content:center;
  background:rgba(22,22,23,.92);backdrop-filter:blur(16px)}
.lb.open{display:flex;animation:fadeIn .25s ease}
@keyframes fadeIn{from{opacity:0}}
.lb figure{text-align:center;animation:pop .35s cubic-bezier(.2,.8,.3,1.1)}
@keyframes pop{from{transform:scale(.95);opacity:0}}
.lb img{max-width:92vw;max-height:74vh;width:auto;height:auto;margin:0 auto;border-radius:14px}
.lb figcaption b{display:block;font-size:17px;color:#fff;margin-top:16px;font-weight:650}
.lb figcaption span{font-size:13px;color:#a1a1a6}
.lb button{position:fixed;top:50%;transform:translateY(-50%);width:48px;height:48px;border-radius:50%;
  border:1px solid rgba(255,255,255,.25);background:rgba(255,255,255,.1);color:#fff;font-size:19px;cursor:pointer;transition:.25s}
.lb button:hover{background:rgba(255,255,255,.22)}
.lb-prev{left:max(16px,3vw)}.lb-next{right:max(16px,3vw)}
.lb button.lb-close{position:fixed;top:18px;right:18px;transform:none;width:42px;height:42px}
.lb-count{position:fixed;bottom:20px;left:50%;transform:translateX(-50%);font-size:12px;color:#a1a1a6;letter-spacing:.2em}

/* ---------- reveal ---------- */
.reveal{opacity:0;transform:translateY(26px);transition:opacity .8s cubic-bezier(.2,.65,.25,1),transform .8s cubic-bezier(.2,.65,.25,1)}
.reveal.in{opacity:1;transform:none}
@media (prefers-reduced-motion:reduce){
  *,*::before,*::after{animation-duration:.001s!important;transition-duration:.001s!important}
  html{scroll-behavior:auto}.reveal{opacity:1;transform:none}
}

.avatar img{width:100%;height:100%;object-fit:cover;border-radius:inherit}

/* ---- 视频卡片 ---- */
.work .media{position:relative}
.vbadge{position:absolute;top:12px;right:12px;z-index:3;font-size:11px;letter-spacing:.06em;color:#fff;background:rgba(20,22,26,.55);backdrop-filter:blur(6px);padding:4px 11px;border-radius:99px;pointer-events:none}
video.peek{position:absolute;inset:0;width:100%;height:100%;object-fit:cover;opacity:0;transition:opacity .55s;pointer-events:none}
.work:hover video.peek{opacity:1}
.lb video{display:none;max-width:92vw;max-height:74vh;width:auto;height:auto;margin:0 auto;border-radius:14px}
.lb video.on{display:block}


/* ---- 首屏动效：蒙版揭示 + 主视觉电影感开场 ---- */
.hero .eyebrow,.hero .sub,.hero .links,.hero .hero-strip,.hero .corner,.hero .wm{opacity:0;transform:translateY(22px);transition:opacity .9s cubic-bezier(.2,.65,.25,1),transform .9s cubic-bezier(.2,.65,.25,1)}
.hero .eyebrow{transition-delay:.05s}
.hero .sub{transition-delay:.52s}
.hero .links{transition-delay:.64s}
.hero .hero-strip{transition-delay:.78s}
.hero .corner{transition-delay:.9s}
.hero .wm{transition:opacity 1.4s .5s cubic-bezier(.2,.65,.25,1)}
body.loaded .hero .eyebrow,body.loaded .hero .sub,body.loaded .hero .links,body.loaded .hero .hero-strip,body.loaded .hero .corner,body.loaded .hero .wm{opacity:1;transform:none}
.hero-title .line{display:block}
.hero-title .ch{display:inline-block;opacity:0;transform:translateY(.42em);filter:blur(7px);transition:opacity .55s cubic-bezier(.2,.65,.25,1),transform .55s cubic-bezier(.2,.65,.25,1),filter .55s cubic-bezier(.2,.65,.25,1)}
body.loaded .hero-title .ch{opacity:1;transform:none;filter:blur(0)}
.hero-title.interactive .ch{transition:none;will-change:transform}
@media (prefers-reduced-motion:reduce){
  .hero .eyebrow,.hero .sub,.hero .links,.hero .hero-strip,.hero .corner,.hero .wm,.hero-title .ch{opacity:1!important;transform:none!important;transition:none!important}
}

/* ============ 作品横向条带 ============ */
.strip{position:relative;min-width:0}
.strip .works,.strip .works-grid,.strip .f-works{cursor:grab;max-width:100%}
.strip .works.nosnap,.strip .works-grid.nosnap,.strip .f-works.nosnap,
.strip .dragging{scroll-snap-type:none!important}
.strip .works.dragging,.strip .works-grid.dragging,.strip .f-works.dragging{cursor:grabbing}
.strip .work{user-select:none;scroll-snap-align:center}
.strip .work img,.strip .work video.peek{-webkit-user-drag:none;pointer-events:none}
.strip .works .work{flex:0 0 auto;width:clamp(330px,42vw,600px)}
.strip .works .work.tall{width:clamp(240px,26vw,390px)}
@media(max-width:640px){.strip .works .work{width:80vw}.strip .works .work.tall{width:56vw}}
.strip-arrow{position:absolute;top:38%;transform:translateY(-50%);width:46px;height:46px;border-radius:50%;
  border:1px solid var(--hair);background:rgba(255,255,255,.94);color:var(--text);
  box-shadow:0 10px 28px -10px rgba(0,0,0,.28);font-size:21px;line-height:1;font-family:var(--sans,inherit);cursor:pointer;
  opacity:0;pointer-events:none;transition:opacity .25s,transform .25s;z-index:3;display:grid;place-items:center}
.strip-arrow.prev{left:14px}
.strip-arrow.next{right:14px}
.strip:hover .strip-arrow:not(.hide),.strip-arrow:focus-visible{opacity:1;pointer-events:auto}
.strip-arrow.hide{opacity:0!important;pointer-events:none!important}
.strip-arrow:hover{transform:translateY(-50%) scale(1.07)}
.strip-arrow:active{transform:translateY(-50%) scale(.94)}
.strip-foot{display:flex;align-items:center;gap:16px;margin-top:14px}
.strip-hint{font-size:12px;letter-spacing:.02em;color:var(--text2);white-space:nowrap;transition:opacity .5s}
.strip-hint.off{opacity:0}
.strip-bar{flex:1;height:2px;border-radius:2px;background:rgba(0,0,0,.08);overflow:hidden}
.strip-bar i{display:block;height:100%;width:100%;border-radius:2px;background:var(--text);transform-origin:0 50%;transform:scaleX(0);transition:transform .12s linear}
@media(max-width:640px){
  .strip-arrow{display:none}
  .strip-hint{display:none}
}
/* ============ 通栏条带 + 简介重排 ============ */
/* 左轨悬挂：简介/引文缩进到名字·头衔同一条文字轴（头像+编号作左轨），单列每句一行，消除之字形阅读 */
/* 186 = 头像 76 + 间距 22 + 编号 66 + 间距 22 */
.a-bio{display:flex;flex-direction:column;gap:10px;align-items:flex-start;margin:0 0 0 186px;max-width:620px}
.a-bio p{margin-bottom:0}
.a-bio blockquote{white-space:nowrap;margin-top:2px}
@media(max-width:960px){
  .a-bio{margin-left:0;max-width:none}
  .a-bio blockquote{white-space:normal}
}
.strip-foot{max-width:1040px;margin:16px auto 0;padding:0 22px}

/* ============ Q&A ============ */
.qa{padding:96px 0;background:var(--bg)}
.qa h2{font-size:clamp(26px,3.4vw,38px);margin-bottom:38px}
.qa h2 .en{margin-left:14px;font-size:.5em;color:var(--text2);font-weight:600;letter-spacing:.1em;vertical-align:2px}
.qa-list{max-width:840px}
.qa-item{border-bottom:1px solid var(--hair)}
.qa-item:first-child{border-top:1px solid var(--hair)}
.qa-q{width:100%;display:flex;justify-content:space-between;align-items:center;gap:20px;background:none;border:none;padding:22px 4px;font-size:17px;font-weight:600;color:var(--text);cursor:pointer;text-align:left;font-family:inherit;transition:color .25s}
.qa-q:hover{color:var(--blue)}
.qa-ico{position:relative;width:24px;height:24px;flex:none;border-radius:50%;background:var(--bg2);transition:transform .4s cubic-bezier(.2,.7,.25,1),background .3s}
.qa-ico::before,.qa-ico::after{content:"";position:absolute;left:50%;top:50%;width:10px;height:1.6px;background:var(--text);transform:translate(-50%,-50%);transition:background .3s}
.qa-ico::after{transform:translate(-50%,-50%) rotate(90deg)}
.qa-item.open .qa-ico{transform:rotate(45deg);background:var(--blue)}
.qa-item.open .qa-ico::before,.qa-item.open .qa-ico::after{background:#fff}
.qa-a{display:grid;grid-template-rows:0fr;transition:grid-template-rows .5s cubic-bezier(.2,.7,.25,1)}
.qa-item.open .qa-a{grid-template-rows:1fr}
.qa-a-in{overflow:hidden}
.qa-a-in p{font-size:14.5px;color:var(--text2);line-height:1.85;padding:2px 4px 24px;max-width:700px}
.qa-a-in ul{margin:0 0 24px;padding-left:18px;font-size:14.5px;color:var(--text2);line-height:2.1;max-width:700px}
@media(max-width:640px){.qa{padding:72px 0}.qa-q{font-size:15.5px;padding:18px 2px}}

/* ============ 作者头像 ============ */
.a-ava{width:76px;height:76px;border-radius:50%;object-fit:cover;border:1px solid var(--hair);box-shadow:0 12px 28px -14px rgba(0,0,0,.35);flex:none;margin-top:4px}
@media(max-width:640px){.a-ava{width:60px;height:60px}}

/* ============ Coverflow 3D 轮播（移植自 React CoverflowCarousel） ============ */
.strip.cf{overflow:hidden;padding:26px 0 4px}
.strip.cf .works{
  display:block;position:relative;margin:0 auto;
  height:calc(var(--cf-card) * 9 / 16);
  perspective:calc(var(--cf-card) * 3);
  transform-style:preserve-3d;
  touch-action:pan-y;
  overflow:visible;scroll-snap-type:none;padding:0;
}
.strip.cf .works{pointer-events:none}   /* preserve-3d 父层平面会挡住后方侧卡的命中，放行给卡片 */
.strip.cf .work{pointer-events:auto}
.strip.cf .work{
  position:absolute;left:50%;top:0;margin:0;
  width:var(--cf-card);aspect-ratio:16/9;
  transition:box-shadow .3s;               /* transform 由 JS 逐帧驱动，不能有过渡 */
  will-change:transform,opacity;
  box-shadow:0 24px 48px -24px rgba(0,0,0,.4);
}
.strip.cf .work.tall{width:var(--cf-card)}
.strip.cf .work .media,.strip.cf .work .media img,.strip.cf .work video.peek{width:100%;height:100%;aspect-ratio:auto;object-fit:cover}
.strip.cf .work .media{position:static}
.strip.cf .work figcaption{display:none}         /* 标题改由中央说明位展示 */
.strip.cf .work.is-center{cursor:zoom-in}
.strip.cf .work:not(.is-center){cursor:pointer}
.strip.cf{--cf-card:clamp(340px,min(40vw,calc((100svh - 550px)*16/9)),600px)}
/* 高个子宽屏：卡片放大一档（720 上限），吃掉多余留白；笔记本小屏不适用，保证整屏放得下 */
@media(min-width:1500px) and (min-height:960px){
  .strip.cf{--cf-card:clamp(340px,min(40vw,calc((100svh - 560px)*16/9)),760px)}
}
@media(max-width:640px){.strip.cf{--cf-card:78vw;padding:26px 0 0}}

/* 竖版轮播（9:16 海报整张展示）：卡高与横版一致、宽收成 9:16；间距/景深 JS 按实测卡宽自适配 */
.strip.cf.portrait{--cf-h:calc(var(--cf-card) * 9 / 16)}
.strip.cf.portrait .work{width:calc(var(--cf-h) * 9 / 16);aspect-ratio:9/16}
@media(max-width:640px){
  /* 手机上沿用卡高会只剩 ~25vw 太窄，单独定宽 46vw，容器高度同步修正 */
  .strip.cf.portrait .work{width:46vw}
  .strip.cf.portrait .works{height:calc(46vw * 16 / 9)}
}

/* 4:3 视频封面（poster43）：a9 只常驻三张，横向有富余——在横版卡的高度预算上放大 ~1.14 倍，
   整张封面不裁切；works 容器高度同步放大，靠回收 padding/caption 的留白保持区块一屏 */
.strip.cf.poster43{--p43w:calc(var(--cf-card) * 9 / 16 * 4 / 3 * 1.14);padding:12px 0 4px}
.strip.cf.poster43 .works{height:calc(var(--p43w) * 3 / 4)}
.strip.cf.poster43 .work{width:var(--p43w);aspect-ratio:4/3}
.strip.cf.poster43 .cf-caption{margin-top:14px}

/* 中央作品说明 */
.strip.cf .cf-caption{display:flex;flex-direction:column;align-items:center;gap:4px;min-height:54px;margin:20px auto 0;text-align:center;padding:0 22px}
.strip.cf .cf-caption b{font-size:17px;font-weight:650}
.strip.cf .cf-caption span{font-size:12.5px;color:var(--text2)}
.strip.cf .cf-caption.swap{animation:cf-swap .45s cubic-bezier(.2,.7,.25,1)}
@keyframes cf-swap{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:none}}

/* 圆点 + 提示 */
.strip.cf .cf-foot{display:flex;align-items:center;justify-content:center;gap:18px;margin-top:14px}
.strip.cf .cf-dots{display:flex;gap:8px}
.strip.cf .cf-dots button{width:8px;height:8px;padding:0;border:none;border-radius:50%;background:var(--text);opacity:.22;cursor:pointer;transition:opacity .3s,transform .3s}
.strip.cf .cf-dots button.on{opacity:1;transform:scale(1.2)}
.strip.cf .strip-hint{font-size:12px;color:var(--text2)}

/* 箭头压到卡片之上；旧进度条/旧脚位停用 */
.strip.cf .strip-arrow{z-index:200;top:calc(26px + var(--cf-card)*9/32)}
.strip.cf .strip-bar,.strip.cf .strip-foot{display:none}
@media(max-width:640px){.strip.cf .strip-arrow{display:none}}

/* ============ 抖音主页外链（与讲师名字同一行） ============ */
.a-name{display:flex;align-items:center;gap:16px;flex-wrap:wrap}
.a-dy{display:inline-flex;align-items:center;gap:7px;padding:7px 15px;
  border:1px solid var(--hair);border-radius:999px;font-size:12.5px;color:var(--text2);
  transition:color .25s,border-color .25s,transform .25s}
.a-dy svg{width:14px;height:14px;fill:currentColor;flex:none}
.a-dy .en{font-size:11px}
.a-dy:hover{color:var(--blue);border-color:var(--blue);transform:translateY(-1px)}

/* ============ 页脚备案 ============ */
.beian{margin-top:22px;font-size:12px;color:var(--text2);display:flex;gap:18px;justify-content:center;flex-wrap:wrap}
.beian a{color:var(--text2);text-decoration:none;border-bottom:1px solid transparent;transition:color .2s,border-color .2s}
.beian a:hover{color:var(--blue);border-color:var(--blue)}