/* 깊이와 통찰 · 교재 컬렉션 — 미니멀 럭셔리 (Apple-inspired) */
:root{
  --bg:#000000; --bg2:#0B0B0D; --panel:#111114;
  --ink:#F5F5F7; --ink2:#D6D6DB; --mut:#8A8A90; --mut2:#5B5B62;
  --line:rgba(255,255,255,.09); --line2:rgba(255,255,255,.05);
  --acc:#C6A15B;                       /* 절제된 골드, 극소량만 */
  --r:18px;
  --ease:cubic-bezier(.22,.61,.36,1);
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{background:var(--bg);color:var(--ink);font-family:'Inter','Noto Sans KR',sans-serif;font-weight:300;line-height:1.6;letter-spacing:-.01em;-webkit-font-smoothing:antialiased;overflow-x:hidden}
a{color:inherit;text-decoration:none}
.skip{position:absolute;left:-9999px;top:0;z-index:400;background:var(--ink);color:#000;padding:10px 18px;border-radius:0 0 10px 0;font-size:14px;font-weight:500}
.skip:focus{left:0}
.wrap{max-width:1120px;margin:0 auto;padding:0 32px}
.reveal{opacity:0;transform:translateY(26px);transition:opacity 1s var(--ease),transform 1s var(--ease)}
.reveal.in{opacity:1;transform:none}

/* ---------- NAV ---------- */
.nav{position:fixed;top:0;left:0;right:0;z-index:50;height:64px;display:flex;align-items:center;transition:background .4s,border-color .4s;border-bottom:1px solid transparent}
.nav.solid{background:rgba(0,0,0,.62);backdrop-filter:saturate(160%) blur(20px);border-bottom-color:var(--line2)}
.nav .wrap{display:flex;align-items:center;gap:14px;width:100%;max-width:1200px;padding:0 30px}
.nav-left{display:flex;align-items:center;gap:14px}
@media(max-width:560px){.nav-left{gap:9px}}
.nav-brand{display:flex;align-items:center;gap:11px}
.nav-logo{height:20px;width:auto;filter:brightness(0) invert(1);opacity:.92}
.nav-div{width:1px;height:16px;background:var(--line)}
.nav-label{display:flex;flex-direction:column;line-height:1.05;color:var(--ink2);font-size:12.5px;font-weight:600;letter-spacing:.01em}
.nav-label em{font-style:normal;font-size:8.5px;font-weight:400;letter-spacing:.16em;text-transform:uppercase;color:var(--mut2);margin-top:2px}
@media(max-width:560px){.nav-label em{display:none}}
.nav-burger{display:none;align-items:center;gap:8px;background:none;border:0;cursor:pointer;padding:8px 4px}
.nb-txt{font-size:13.5px;font-weight:500;color:var(--ink)}
.nb-ico{display:flex;flex-direction:column;gap:5px}
.nb-ico i{display:block;width:22px;height:1.5px;background:var(--ink);transition:.3s}
.nav-menu{position:absolute;left:50%;transform:translateX(-50%);display:flex;gap:30px}
.nav-menu a{font-size:14px;color:var(--ink2);transition:.3s}
.nav-menu a:hover{color:var(--ink)}
.nav-cta{display:inline-flex;align-items:center;margin-left:auto;padding:8px 17px;border-radius:100px;border:1px solid rgba(255,255,255,.2);color:rgba(255,255,255,.85);font-size:13.5px;font-weight:500;white-space:nowrap;transition:.3s}
.nav-cta:hover{border-color:rgba(255,255,255,.5);color:var(--ink)}
@media(max-width:860px){
  .nav-menu{display:none;position:absolute;top:64px;left:0;right:0;transform:none;flex-direction:column;gap:0;background:rgba(0,0,0,.94);backdrop-filter:blur(20px);border-bottom:1px solid var(--line2);padding:8px 0}
  .nav-menu.open{display:flex}
  .nav-menu a{padding:15px 30px;border-bottom:1px solid var(--line2)}
  .nav-burger{display:flex}
  .nav-eco{margin-left:auto}
  .nav-cta{display:none}
}
#shelves,#math{scroll-margin-top:80px}
/* 수학 · 준비 중 (콘텐츠 자리) */
.math-soon .soon-panel{display:flex;flex-direction:column;align-items:center;gap:26px;text-align:center;padding:60px 30px;border:1px dashed rgba(255,255,255,.15);border-radius:20px;margin-top:22px;background:rgba(255,255,255,.02)}
.math-soon .soon-lab{max-width:220px;width:100%;height:auto;filter:brightness(0) invert(1);opacity:.5}
.math-soon .soon-text{font-size:14.5px;color:var(--mut);line-height:1.75;max-width:520px}
/* 상세 시트 · 전시 안내 */
.d-exhibit{margin-top:20px;font-size:13.5px;color:var(--mut);line-height:1.6}
.d-exhibit b{color:var(--ink)}
.social{display:flex;gap:2px}
.soc{display:inline-flex;align-items:center;justify-content:center;width:32px;height:32px;border-radius:8px;color:var(--mut);transition:.25s}
.soc:hover{color:var(--ink);background:rgba(255,255,255,.06)}
.btn{background:none;border:none;color:var(--ink2);font:400 13px 'Noto Sans KR';padding:8px 4px;cursor:pointer;transition:.25s;letter-spacing:0}
.btn:hover{color:var(--ink)}
.btn.primary{background:var(--ink);color:#000;border-radius:100px;padding:8px 18px;font-weight:500}
.btn.primary:hover{opacity:.85}

/* ---------- HERO ---------- */
.hero{min-height:100vh;display:flex;flex-direction:column;align-items:center;justify-content:center;text-align:center;position:relative;padding:120px 24px 80px}
.hero::after{content:'';position:absolute;left:50%;bottom:34px;width:1px;height:46px;background:linear-gradient(var(--mut2),transparent);transform:translateX(-50%)}
.cobrand{display:flex;align-items:center;justify-content:center;gap:30px;margin-bottom:52px;opacity:0;animation:cbIn 1.3s var(--ease) .2s forwards}
@keyframes cbIn{to{opacity:1}}
.cb-logo{height:34px;width:auto;filter:brightness(0) invert(1);opacity:.9}
.cb-logo.cb-lab{height:44px;opacity:.8}
.cb-x{font-size:17px;font-weight:200;color:var(--mut2)}
@media(max-width:640px){.cobrand{gap:20px}.cb-logo{height:28px}.cb-logo.cb-lab{height:36px}}
.hero-kick{font-size:12px;font-weight:500;letter-spacing:.32em;color:var(--mut);margin-bottom:34px}
.hero h1{font-weight:200;font-size:clamp(40px,7.4vw,88px);line-height:1.06;letter-spacing:-.03em;white-space:pre-line}
.hero-sub{margin-top:34px;font-size:clamp(15px,2vw,19px);font-weight:300;color:var(--mut);line-height:1.75;white-space:pre-line;max-width:560px}
.hero-stats{display:flex;gap:0;margin-top:64px;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.hero-stats .stat{padding:24px 34px;position:relative}
.hero-stats .stat+.stat::before{content:'';position:absolute;left:0;top:24px;bottom:24px;width:1px;background:var(--line)}
.stat .n{font-weight:300;font-size:34px;letter-spacing:-.02em;font-variant-numeric:tabular-nums}
.stat .n .plus{color:var(--acc);font-size:22px;vertical-align:top;margin-left:1px}
.stat .n .suf{font-size:17px;color:var(--mut);margin-left:2px}
.stat .l{font-size:11.5px;color:var(--mut);letter-spacing:.06em;margin-top:8px}

/* ---------- IDENTITY BAND ---------- */
.identity{padding:92px 0;text-align:center;background:#F7F5EF;border-top:1px solid #E7E4DB;border-bottom:1px solid #E7E4DB}
.identity .id-line{color:#1A1A1F}
.identity .id-line b{color:#000}
.identity .id-sub{color:#7A7A82}
.identity .id-lnk{border-color:#DCD8CC;color:#3A3A40}
.identity .id-lnk:hover{border-color:rgba(0,0,0,.28);background:rgba(0,0,0,.03);color:#000}
.identity .id-lnk .arw{color:#9C7C39}
.id-line{font-size:clamp(16px,2.1vw,21px);font-weight:300;color:var(--ink2);letter-spacing:-.01em;line-height:1.6}
.id-line b{font-weight:600;color:var(--ink)}
.id-sub{margin-top:12px;font-size:13.5px;color:var(--mut);letter-spacing:.01em}
.id-links{display:flex;justify-content:center;flex-wrap:wrap;gap:12px;margin-top:26px}
.id-lnk{display:inline-flex;align-items:center;gap:6px;padding:9px 18px;border:1px solid var(--line);border-radius:100px;font-size:13px;color:var(--ink2);letter-spacing:.01em;transition:border-color .35s var(--ease),color .35s var(--ease),background .35s var(--ease)}
.id-lnk:hover{border-color:rgba(255,255,255,.28);background:rgba(255,255,255,.03);color:var(--ink)}
.id-lnk .arw{font-size:11px;color:var(--mut2);transition:transform .35s var(--ease)}
.id-lnk:hover .arw{transform:translate(2px,-2px);color:var(--acc)}

/* ---------- SERIES SECTION ---------- */
.series{padding:132px 0 116px;text-align:center;position:relative}
.series+.series{border-top:1px solid var(--line2)}
.series-ko{font-size:12.5px;font-weight:500;letter-spacing:.24em;color:var(--acc);text-transform:uppercase;margin-bottom:20px}
.series-name{font-weight:200;font-size:clamp(34px,5vw,60px);letter-spacing:-.03em;line-height:1.05}
.series-note{margin-top:12px;font-size:13px;color:var(--mut)}
.grid{display:flex;flex-wrap:wrap;justify-content:center;gap:60px 52px;margin-top:68px}
.book{width:250px;cursor:pointer;text-align:center;transition:transform .5s var(--ease)}
.book:hover{transform:translateY(-8px)}
.book:focus-visible{outline:2px solid var(--acc);outline-offset:8px;border-radius:6px}
.book-cover{width:250px;aspect-ratio:210/297;border-radius:6px;overflow:hidden;position:relative;box-shadow:0 20px 46px -20px rgba(0,0,0,.85),0 0 0 1px var(--line2);background:#0e0e11 center/cover no-repeat;transition:box-shadow .5s var(--ease)}
.book:hover .book-cover{box-shadow:0 34px 70px -22px rgba(0,0,0,.95),0 0 0 1px var(--line)}
.book-cover img{width:100%;height:100%;object-fit:cover;display:block}
.book-cover .wip{position:absolute;top:11px;right:11px;font-size:10px;font-weight:400;letter-spacing:.04em;color:var(--ink);background:rgba(0,0,0,.5);backdrop-filter:blur(6px);border:1px solid var(--line);padding:4px 9px;border-radius:100px}
.book-cover .set-badge{position:absolute;top:11px;left:11px;font-size:10px;font-weight:600;letter-spacing:.04em;color:#0C1A33;background:rgba(255,255,255,.9);backdrop-filter:blur(6px);padding:4px 9px;border-radius:100px}
.book-lead{margin-top:20px;font-size:14px;font-weight:400;color:var(--ink2);letter-spacing:-.01em}
.book-title{margin-top:7px;font-size:12.5px;color:var(--mut);font-weight:300}
.book-grade{margin-top:3px;font-size:11.5px;color:var(--mut2);letter-spacing:.02em}

/* ---------- DETAIL (풀스크린) ---------- */
.ov{position:fixed;inset:0;z-index:100;background:rgba(0,0,0,.6);backdrop-filter:blur(3px);opacity:0;pointer-events:none;transition:opacity .4s}
.ov.open{opacity:1;pointer-events:auto}
.sheet{position:fixed;inset:0;z-index:101;background:var(--bg);overflow-y:auto;transform:translateY(24px);opacity:0;pointer-events:none;transition:transform .5s var(--ease),opacity .4s}
.sheet.open{transform:none;opacity:1;pointer-events:auto}
.sheet-close{position:fixed;top:22px;right:26px;z-index:110;width:40px;height:40px;border-radius:50%;background:rgba(255,255,255,.07);border:none;color:var(--ink);font-size:20px;cursor:pointer;backdrop-filter:blur(10px);transition:.25s}
.sheet-close:hover{background:rgba(255,255,255,.14)}
.d-hero{min-height:88vh;display:grid;grid-template-columns:1fr 1fr;align-items:center;gap:40px;max-width:1120px;margin:0 auto;padding:100px 40px 40px}
.d-cover{display:flex;justify-content:center;align-items:center}
.d-cover img{width:min(360px,80%);height:auto;border-radius:8px;box-shadow:0 50px 100px -30px rgba(0,0,0,.9),0 0 0 1px var(--line2)}
.d-info{max-width:440px}
.d-ko{font-size:12.5px;letter-spacing:.22em;color:var(--acc);text-transform:uppercase;font-weight:500}
.d-title{font-weight:200;font-size:clamp(34px,4.6vw,52px);letter-spacing:-.03em;line-height:1.04;margin-top:16px}
.d-lead{margin-top:22px;font-size:22px;font-weight:300;color:var(--ink);letter-spacing:-.01em;line-height:1.4}
.d-desc{margin-top:16px;font-size:15.5px;font-weight:300;color:var(--mut);line-height:1.8}
.d-meta{display:flex;flex-wrap:wrap;gap:0;margin-top:30px;border-top:1px solid var(--line)}
.d-meta>div{padding:16px 26px 16px 0;margin-right:26px;border-right:1px solid var(--line);flex:0 0 auto}
.d-meta>div:last-child{border-right:none;margin-right:0;padding-right:0}
.d-meta .k{font-size:11px;color:var(--mut);letter-spacing:.04em}
.d-meta .v{font-weight:400;font-size:14.5px;margin-top:6px;color:var(--ink)}
.d-pub{display:flex;align-items:center;gap:13px;margin-top:40px;padding-top:26px;border-top:1px solid var(--line2)}
.d-pub img{height:18px;filter:brightness(0) invert(1);opacity:.62}
.d-pub img:last-of-type{height:22px;opacity:.5}
.d-pub .pdiv{width:1px;height:18px;background:var(--line)}
.d-pub .ptxt{font-size:11px;color:var(--mut2);line-height:1.5;letter-spacing:.03em;margin-left:2px}

/* lightbox */
.lb{position:fixed;inset:0;z-index:200;background:rgba(0,0,0,.94);display:flex;align-items:center;justify-content:center;cursor:zoom-out;opacity:0;pointer-events:none;transition:.3s}
.lb.open{opacity:1;pointer-events:auto}
.lb img{max-width:90vw;max-height:90vh;border-radius:6px;box-shadow:0 40px 100px rgba(0,0,0,.6)}

/* toast */
.toast{position:fixed;bottom:32px;left:50%;transform:translateX(-50%) translateY(16px);background:rgba(30,30,34,.9);backdrop-filter:blur(14px);color:var(--ink);font-weight:400;font-size:13.5px;padding:13px 22px;border-radius:12px;z-index:300;opacity:0;transition:.35s var(--ease);box-shadow:0 0 0 1px var(--line)}
.toast.show{opacity:1;transform:translateX(-50%) translateY(0)}

/* footer */
.foot{border-top:1px solid var(--line2);padding:70px 0 80px;text-align:center}
.foot-lockup{display:inline-flex;align-items:center;gap:18px;margin-bottom:22px}
.foot-logo{height:26px;filter:brightness(0) invert(1);opacity:.85}
.foot-div{width:1px;height:26px;background:var(--line)}
.foot-lab{height:30px;filter:brightness(0) invert(1);opacity:.7}
.foot-brand{font-size:13px;color:var(--mut);line-height:1.9}
.foot-brand b{color:var(--ink2);font-weight:500}
.foot .social{justify-content:center;margin-top:22px}
.foot-copy{margin-top:30px;font-size:11.5px;color:var(--mut2);letter-spacing:.02em}

@media(max-width:820px){
  .d-hero{grid-template-columns:1fr;text-align:center;gap:30px;padding-top:80px}
  .d-info{max-width:none;margin:0 auto}
  .d-meta{justify-content:center}
  .hero-stats{flex-wrap:wrap}
}