/* ==========================================================
   prim — product pages (paperback / hardcover / collector's)
   Builds on css/site.css tokens and components.
   ========================================================== */

/* ---------- Header cart button ---------- */
.cart-btn{position:relative;width:42px;height:42px;border-radius:12px;border:1px solid var(--line);display:grid;place-items:center;transition:.25s}
.cart-btn:hover{border-color:var(--sky);background:var(--sky-soft)}
.cart-btn svg{width:19px;height:19px}
.cart-count{position:absolute;top:-6px;right:-6px;min-width:19px;height:19px;padding:0 5px;border-radius:99px;background:var(--sky);color:var(--black);font-size:11px;font-weight:800;display:grid;place-items:center;transform:scale(0);transition:transform .35s cubic-bezier(.2,1.6,.4,1)}
.cart-count.on{transform:scale(1)}
.cart-count.bump{animation:bump .45s}
@keyframes bump{40%{transform:scale(1.35)}}

/* ---------- Breadcrumb ---------- */
.crumbs{display:flex;align-items:center;gap:8px;font-size:13px;color:var(--muted);padding:22px 0 0;flex-wrap:wrap}
.crumbs a:hover{color:var(--white)}
.crumbs span{opacity:.4}
.crumbs b{color:var(--white);font-weight:600}

/* ---------- Product top ---------- */
.pd{padding:24px 0 90px;position:relative}
.pd::before{content:"";position:absolute;inset:-120px 0 auto;height:760px;pointer-events:none;
  background:radial-gradient(520px 380px at 28% 40%,var(--glow,rgba(29,78,216,.32)),transparent 70%)}
.pd-grid{position:relative;display:grid;grid-template-columns:minmax(0,1.08fr) minmax(0,.92fr);gap:56px;align-items:start}

/* gallery */
.gallery{position:sticky;top:92px}
.g-main{position:relative;border-radius:28px;border:1px solid var(--line);overflow:hidden;
  background:radial-gradient(circle at 50% 45%,var(--glow,rgba(29,78,216,.35)),transparent 62%),linear-gradient(180deg,#0a1222,#05070b)}
.g-track{display:flex;overflow-x:auto;scroll-snap-type:x mandatory;scrollbar-width:none;aspect-ratio:1/1.02}
.g-track::-webkit-scrollbar{display:none}
.g-slide{flex:0 0 100%;scroll-snap-align:center;display:grid;place-items:center;position:relative;perspective:1600px;overflow:hidden}
.g-slide .grid-bg{position:absolute;inset:0;background-image:linear-gradient(var(--line) 1px,transparent 1px),linear-gradient(90deg,var(--line) 1px,transparent 1px);background-size:48px 48px;mask-image:radial-gradient(circle at 50% 50%,#000,transparent 70%);-webkit-mask-image:radial-gradient(circle at 50% 50%,#000,transparent 70%);opacity:.6}
.g-badge{position:absolute;top:18px;left:18px;z-index:3;display:flex;gap:8px;flex-wrap:wrap}
.g-badge span{font-size:11px;font-weight:800;letter-spacing:.06em;text-transform:uppercase;padding:6px 11px;border-radius:999px;background:var(--white);color:var(--black)}
.g-badge span.alt{background:rgba(5,7,11,.7);color:var(--sky);border:1px solid rgba(108,196,255,.4);backdrop-filter:blur(8px)}
.g-count{position:absolute;bottom:18px;right:18px;z-index:3;font-size:12px;font-weight:700;padding:6px 11px;border-radius:999px;background:rgba(5,7,11,.7);border:1px solid var(--line);color:var(--muted)}
.g-nav{position:absolute;top:50%;z-index:3;width:44px;height:44px;border-radius:50%;display:grid;place-items:center;background:rgba(5,7,11,.6);border:1px solid var(--line);backdrop-filter:blur(8px);transform:translateY(-50%);transition:.25s}
.g-nav:hover{border-color:var(--sky);background:var(--sky-soft)}
.g-nav svg{width:18px;height:18px}
.g-prev{left:16px}.g-next{right:16px}
.g-label{position:absolute;bottom:18px;left:18px;z-index:3;font-size:12px;font-weight:700;letter-spacing:.14em;text-transform:uppercase;color:var(--muted)}

/* product book (bigger, interactive) */
.pbook{--rx:6deg;--ry:-20deg;width:min(46%,290px);padding:clamp(20px,3vw,32px) clamp(16px,2.4vw,26px) clamp(16px,2.4vw,26px) clamp(24px,3.2vw,36px);
  transform:rotateY(var(--ry)) rotateX(var(--rx));transition:transform .5s cubic-bezier(.2,.8,.2,1)}
.pbook .bk-title{font-size:clamp(26px,3.6vw,40px)}
.pbook .bk-top{font-size:clamp(8px,.8vw,10px);white-space:nowrap}
.pbook .bk-mark{width:clamp(30px,3.6vw,46px);height:clamp(30px,3.6vw,46px)}
.pbook-wrap{position:relative;display:grid;place-items:center;width:100%;height:100%}
.pbook-wrap::after{content:"";position:absolute;bottom:14%;left:50%;width:44%;height:24px;transform:translateX(-50%);background:radial-gradient(ellipse,rgba(0,0,0,.8),transparent 70%);filter:blur(6px);z-index:-1}
.pbook .edge{position:absolute;top:3px;bottom:3px;right:-12px;width:12px;border-radius:0 3px 3px 0;transform:rotateY(90deg);transform-origin:left;
  background:repeating-linear-gradient(180deg,#e9eef7 0 1px,#c9d3e3 1px 2px)}
.foil{position:absolute;inset:0;background:linear-gradient(115deg,transparent 30%,rgba(255,255,255,.22) 45%,rgba(108,196,255,.25) 50%,transparent 62%);mix-blend-mode:screen;opacity:.8;pointer-events:none}

/* back cover */
.pback{width:min(46%,290px);aspect-ratio:2/3;border-radius:12px 4px 4px 12px;padding:28px 24px;display:flex;flex-direction:column;gap:14px;
  background:linear-gradient(150deg,var(--c1),var(--c2));box-shadow:30px 40px 80px -20px rgba(0,0,0,.9),0 0 0 1px rgba(108,196,255,.12);transform:rotateY(14deg) rotateX(4deg)}
.pback .quote{font-family:var(--serif);font-weight:700;font-size:clamp(14px,1.5vw,17px);line-height:1.25;letter-spacing:-.01em}
.pback .lines{display:grid;gap:7px;margin-top:4px}
.pback .lines i{height:5px;border-radius:3px;background:rgba(244,248,255,.14)}
.pback .lines i:nth-child(3n){width:70%}
.pback .barcode{margin-top:auto;align-self:flex-end;width:44%;height:40px;border-radius:3px;padding:5px;background:#fff;
  background-image:repeating-linear-gradient(90deg,#000 0 2px,transparent 2px 3px,#000 3px 4px,transparent 4px 7px);background-clip:content-box}

/* open spread */
.spread{width:min(78%,480px);aspect-ratio:3/2;display:grid;grid-template-columns:1fr 1fr;transform:rotateX(26deg);box-shadow:0 50px 80px -30px rgba(0,0,0,.95);border-radius:6px;overflow:hidden}
.spread .page{background:linear-gradient(90deg,#eef2f8,#f8fafd);color:#0b1e3f;padding:clamp(14px,2.4vw,28px);display:flex;flex-direction:column;gap:7px}
.spread .page:first-child{background:linear-gradient(90deg,#f8fafd,#e3e9f2)}
.spread .page small{font-size:9px;letter-spacing:.24em;text-transform:uppercase;font-weight:800;color:#1d4ed8}
.spread .page h4{font-family:var(--serif);font-size:clamp(15px,1.8vw,22px);font-weight:800;letter-spacing:-.03em;line-height:1.05;margin-bottom:4px}
.spread .page i{height:4px;border-radius:2px;background:rgba(11,30,63,.16)}
.spread .page i:nth-child(4n){width:62%}
.spread .pn{margin-top:auto;font-size:9px;color:#64748b;font-weight:700}

/* stack */
.stack{display:grid;gap:6px;transform:rotate(-4deg)}
.stack div{height:clamp(34px,5vw,48px);width:clamp(220px,30vw,320px);border-radius:4px;display:flex;align-items:center;justify-content:space-between;padding:0 18px;
  font-family:var(--serif);font-weight:800;font-size:clamp(12px,1.3vw,15px);letter-spacing:-.01em;box-shadow:0 14px 30px -12px rgba(0,0,0,.9)}
.stack div small{font-family:var(--sans);font-size:9px;letter-spacing:.24em;text-transform:uppercase;opacity:.7}
.stack div:nth-child(1){background:linear-gradient(90deg,#0b1e3f,#05070b);margin-left:14px}
.stack div:nth-child(2){background:linear-gradient(90deg,#1d4ed8,#0b1e3f);margin-left:-8px}
.stack div:nth-child(3){background:linear-gradient(90deg,#e8f2ff,#6cc4ff);color:#05070b;margin-left:6px}
.stack div.me{outline:2px solid var(--sky);outline-offset:3px}

/* thumbs */
.g-thumbs{display:grid;grid-template-columns:repeat(4,1fr);gap:10px;margin-top:12px}
.thumb{aspect-ratio:1;border-radius:16px;border:1px solid var(--line);background:radial-gradient(circle,rgba(29,78,216,.25),transparent 70%),var(--ink);display:grid;place-items:center;transition:.25s;position:relative}
.thumb:hover{border-color:rgba(108,196,255,.35)}
.thumb.on{border-color:var(--sky);box-shadow:0 0 0 3px rgba(108,196,255,.15)}
.thumb .t-front,.thumb .t-back{width:30%;aspect-ratio:2/3;border-radius:2px 5px 5px 2px;background:linear-gradient(150deg,var(--c1),var(--c2));box-shadow:0 6px 14px -4px #000}
.thumb .t-back{border-radius:5px 2px 2px 5px;position:relative}
.thumb .t-back::after{content:"";position:absolute;right:12%;bottom:10%;width:40%;height:14%;background:#fff;border-radius:1px}
.thumb .t-open{width:56%;aspect-ratio:3/2;background:linear-gradient(90deg,#f8fafd 49%,#cbd5e1 50%,#f8fafd 51%);border-radius:2px;transform:perspective(200px) rotateX(24deg)}
.thumb .t-stack{display:grid;gap:3px;transform:rotate(-4deg)}
.thumb .t-stack i{width:46px;height:9px;border-radius:2px;background:#0b1e3f}
.thumb .t-stack i:nth-child(2){background:#1d4ed8}.thumb .t-stack i:nth-child(3){background:#6cc4ff}
.g-dots{display:none;justify-content:center;gap:7px;margin-top:14px}
.g-dots i{width:7px;height:7px;border-radius:99px;background:var(--line);transition:.3s}
.g-dots i.on{width:22px;background:var(--sky)}

/* ---------- Info panel ---------- */
.info{display:flex;flex-direction:column;min-width:0}
.gallery{min-width:0}
.info-badges{display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.ib{display:inline-flex;align-items:center;gap:7px;font-size:12px;font-weight:700;padding:6px 12px;border-radius:999px;border:1px solid var(--line);background:rgba(244,248,255,.03);color:var(--muted)}
.ib.ok{color:#4ade80;border-color:rgba(74,222,128,.25);background:rgba(74,222,128,.06)}
.ib.hot{color:var(--sky);border-color:rgba(108,196,255,.3);background:var(--sky-soft)}
.info h1{font-family:var(--serif);font-weight:800;font-size:clamp(36px,4.4vw,58px);line-height:1;letter-spacing:-.045em;margin:18px 0 8px}
.info h1 em{font-style:normal;background:linear-gradient(120deg,var(--sky),#a5dcff 50%,var(--blue));-webkit-background-clip:text;background-clip:text;color:transparent}
.edition-name{font-size:15px;color:var(--muted);font-weight:600}
.rating-line{display:flex;align-items:center;gap:10px;margin-top:14px;font-size:14px;color:var(--muted)}
.rating-line .stars{font-size:15px}
.rating-line a{text-decoration:underline;text-underline-offset:3px;text-decoration-color:rgba(147,163,189,.4)}
.rating-line a:hover{color:var(--white)}
.price-row{display:flex;align-items:baseline;gap:12px;margin-top:22px;flex-wrap:wrap}
.price-now{font-family:var(--serif);font-size:42px;font-weight:800;letter-spacing:-.04em;line-height:1}
.price-was{font-size:18px;color:var(--muted);text-decoration:line-through}
.save{font-size:12px;font-weight:800;letter-spacing:.04em;padding:5px 10px;border-radius:999px;background:var(--sky);color:var(--black)}
.tax{font-size:12.5px;color:var(--muted);margin-top:6px}
.desc{color:#c3cfe3;margin-top:18px;font-size:15.5px}
.opt-label{display:flex;justify-content:space-between;align-items:center;margin:28px 0 12px;font-size:13px;font-weight:700;letter-spacing:.06em;text-transform:uppercase;color:var(--muted)}
.opt-label b{color:var(--white);text-transform:none;letter-spacing:0;font-size:14px}

/* edition switcher */
.editions{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}
.ed{position:relative;display:flex;flex-direction:column;align-items:center;gap:10px;padding:16px 8px 14px;border-radius:18px;border:1px solid var(--line);background:rgba(10,15,26,.6);text-align:center;transition:.25s}
.ed:hover{border-color:rgba(108,196,255,.4);transform:translateY(-2px)}
.ed.on{border-color:var(--sky);background:linear-gradient(180deg,rgba(29,78,216,.22),rgba(10,15,26,.6));box-shadow:0 0 0 3px rgba(108,196,255,.12)}
.ed .mini{width:30px;height:44px;border-radius:2px 5px 5px 2px;background:linear-gradient(150deg,var(--c1),var(--c2));box-shadow:0 8px 16px -6px #000,0 0 0 1px rgba(108,196,255,.18)}
.ed b{font-size:13.5px;line-height:1.2}
.ed small{font-size:12.5px;color:var(--muted);font-weight:600}
.ed .tick{position:absolute;top:8px;right:8px;width:18px;height:18px;border-radius:50%;background:var(--sky);color:var(--black);display:none;place-items:center}
.ed .tick svg{width:11px;height:11px}
.ed.on .tick{display:grid}

/* bundles */
.bundles{display:grid;gap:10px}
.bundle{position:relative;display:flex;align-items:center;gap:14px;padding:16px 18px;border-radius:18px;border:1px solid var(--line);background:rgba(10,15,26,.6);cursor:pointer;transition:.25s}
.bundle:hover{border-color:rgba(108,196,255,.35)}
.bundle input{position:absolute;opacity:0;pointer-events:none}
.bundle .radio{flex:none;width:20px;height:20px;border-radius:50%;border:1.5px solid rgba(244,248,255,.3);display:grid;place-items:center;transition:.25s}
.bundle .radio::after{content:"";width:10px;height:10px;border-radius:50%;background:var(--sky);transform:scale(0);transition:.25s}
.bundle:has(input:checked){border-color:var(--sky);background:linear-gradient(90deg,rgba(29,78,216,.2),rgba(10,15,26,.6))}
.bundle:has(input:checked) .radio{border-color:var(--sky)}
.bundle:has(input:checked) .radio::after{transform:scale(1)}
.bundle input:focus-visible ~ .radio{outline:2px solid var(--sky);outline-offset:3px}
.b-main{flex:1;min-width:0}
.b-main b{display:block;font-size:15px}
.b-main small{color:var(--muted);font-size:13px}
.b-price{text-align:right;font-weight:800;font-size:16px;line-height:1.2}
.b-price s{display:block;font-weight:500;font-size:12.5px;color:var(--muted)}
.b-tag{position:absolute;top:-10px;right:16px;font-size:10.5px;font-weight:800;letter-spacing:.06em;text-transform:uppercase;padding:4px 9px;border-radius:999px;background:var(--white);color:var(--black)}

/* stock bar */
.stock-box{margin-top:22px;padding:16px 18px;border-radius:16px;border:1px solid var(--line);background:rgba(10,15,26,.5)}
.stock-top{display:flex;justify-content:space-between;font-size:13.5px;font-weight:600}
.stock-top span{color:var(--sky)}
.bar{height:6px;border-radius:99px;background:rgba(244,248,255,.08);margin-top:10px;overflow:hidden}
.bar i{display:block;height:100%;width:0;border-radius:99px;background:linear-gradient(90deg,var(--blue),var(--sky));transition:width 1.6s cubic-bezier(.2,.8,.2,1)}

/* buy */
.buy{display:grid;grid-template-columns:auto 1fr;gap:10px;margin-top:22px}
.qty{display:flex;align-items:center;height:58px;border-radius:999px;border:1px solid var(--line);background:rgba(10,15,26,.6)}
.qty button{width:46px;height:100%;display:grid;place-items:center;font-size:20px;color:var(--muted);transition:.2s}
.qty button:hover{color:var(--white)}
.qty output{min-width:26px;text-align:center;font-weight:800}
.buy .btn{height:58px;font-size:16px;width:100%}
.buy .btn-primary{position:relative;overflow:hidden}
.buy .btn-primary::after{content:"";position:absolute;inset:0;background:linear-gradient(105deg,transparent 35%,rgba(108,196,255,.35) 50%,transparent 65%);transform:translateX(-100%);animation:btnsheen 3.6s ease-in-out infinite 1.2s}
@keyframes btnsheen{45%,100%{transform:translateX(100%)}}
.buy .tg{grid-column:1/-1}
.paylogos{display:flex;justify-content:center;gap:6px;margin-top:14px;flex-wrap:wrap}
.paylogos span{padding:5px 9px;border:1px solid var(--line);border-radius:7px;font-size:10.5px;font-weight:800;letter-spacing:.05em;color:var(--muted)}

/* delivery */
.delivery{margin-top:22px;border-radius:18px;border:1px solid rgba(108,196,255,.18);background:linear-gradient(180deg,rgba(11,30,63,.6),rgba(10,15,26,.6));padding:18px}
.cutoff{display:flex;align-items:center;gap:10px;font-size:14px}
.cutoff .ic{width:34px;height:34px;flex:none}
.cutoff b{color:var(--sky);font-variant-numeric:tabular-nums}
.timeline{display:grid;grid-template-columns:repeat(3,1fr);margin-top:18px;position:relative}
.timeline::before{content:"";position:absolute;top:15px;left:16.6%;right:16.6%;height:1px;background:linear-gradient(90deg,var(--sky),rgba(108,196,255,.2))}
.tl{display:flex;flex-direction:column;align-items:center;text-align:center;gap:4px;position:relative}
.tl i{width:30px;height:30px;border-radius:50%;display:grid;place-items:center;background:var(--black);border:1px solid rgba(108,196,255,.4);color:var(--sky)}
.tl i svg{width:14px;height:14px}
.tl:first-child i{background:var(--sky);color:var(--black);border-color:var(--sky)}
.tl b{font-size:13px;margin-top:4px}
.tl small{font-size:12px;color:var(--muted)}

/* perks */
.perks{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;margin-top:22px}
.perk{display:flex;flex-direction:column;align-items:center;gap:8px;text-align:center;padding:14px 8px;border-radius:16px;background:rgba(244,248,255,.025);border:1px solid var(--line);font-size:12.5px;font-weight:600;color:#c3cfe3;line-height:1.3}
.perk svg{width:20px;height:20px;color:var(--sky)}

/* accordions */
.acc{margin-top:26px;border-top:1px solid var(--line)}
.acc summary{padding:20px 0;font-size:16px}
.acc .ans{padding:0 0 22px;font-size:14.5px}
.acc .plus{width:28px;height:28px}
.spec{display:grid;grid-template-columns:1fr 1fr;gap:0;border:1px solid var(--line);border-radius:14px;overflow:hidden}
.spec div{padding:12px 14px;border-bottom:1px solid var(--line);font-size:13.5px}
.spec div:nth-child(odd){color:var(--muted);border-right:1px solid var(--line)}
.spec div:nth-last-child(-n+2){border-bottom:0}

/* ---------- Sections below ---------- */
.inside{display:grid;grid-template-columns:repeat(4,1fr);gap:16px}
.lesson{padding:28px;border-radius:24px;border:1px solid var(--line);background:linear-gradient(180deg,rgba(11,30,63,.5),rgba(5,7,11,0));position:relative;overflow:hidden;transition:.4s}
.lesson:hover{border-color:rgba(108,196,255,.3);transform:translateY(-4px)}
.lesson .n{font-family:var(--serif);font-size:64px;font-weight:800;letter-spacing:-.05em;line-height:1;background:linear-gradient(180deg,rgba(108,196,255,.55),rgba(108,196,255,0));-webkit-background-clip:text;background-clip:text;color:transparent}
.lesson h3{font-size:18px;font-weight:700;margin:18px 0 8px}
.lesson p{color:var(--muted);font-size:14.5px}

/* edition highlight */
.highlight{display:grid;grid-template-columns:1fr 1fr;gap:56px;align-items:center}
.hl-visual{position:relative;aspect-ratio:1/1;border-radius:32px;overflow:hidden;display:grid;place-items:center;perspective:1400px;border:1px solid var(--line);
  background:radial-gradient(circle at 50% 50%,var(--glow,rgba(29,78,216,.4)),transparent 60%),var(--ink)}
.hl-visual .ring{position:absolute;width:76%;height:76%;border:1px solid rgba(108,196,255,.15);border-radius:50%}
.hl-visual .ring.r2{width:60%;height:60%;border-style:dashed;animation:spin 60s linear infinite}
.hl-visual .pbook{--ry:-26deg;--rx:8deg;width:42%;animation:hlfloat 7s ease-in-out infinite}
@keyframes hlfloat{50%{transform:rotateY(-18deg) rotateX(4deg) translateY(-12px)}}
.hl-list{display:grid;gap:12px;margin-top:30px}
.hl-item{display:flex;gap:16px;padding:18px;border-radius:18px;border:1px solid var(--line);background:rgba(10,15,26,.6)}
.hl-item .ic{flex:none;width:44px;height:44px;border-radius:13px}
.hl-item .ic svg{width:20px;height:20px}
.hl-item b{display:block;font-size:15.5px;margin-bottom:2px}
.hl-item small{color:var(--muted);font-size:14px}

/* compare */
.compare{border:1px solid var(--line);border-radius:26px;overflow:hidden;background:var(--ink)}
.cmp-row{display:grid;grid-template-columns:1.3fr repeat(3,1fr);border-bottom:1px solid var(--line)}
.cmp-row:last-child{border-bottom:0}
.cmp-row>*{padding:18px 20px;font-size:14.5px;display:flex;align-items:center;justify-content:center;text-align:center}
.cmp-row>:first-child{justify-content:flex-start;text-align:left;color:var(--muted);font-weight:600}
.cmp-head>*{flex-direction:column;gap:10px;padding:26px 16px}
.cmp-head .mini{width:34px;height:50px;border-radius:2px 5px 5px 2px;background:linear-gradient(150deg,var(--c1),var(--c2));box-shadow:0 8px 16px -6px #000,0 0 0 1px rgba(108,196,255,.2)}
.cmp-head b{font-size:15px}
.cmp-head small{color:var(--muted);font-weight:700}
.cmp-row .me{background:rgba(29,78,216,.12);box-shadow:inset 1px 0 0 rgba(108,196,255,.25),inset -1px 0 0 rgba(108,196,255,.25)}
.cmp-head .me{box-shadow:inset 1px 0 0 rgba(108,196,255,.25),inset -1px 0 0 rgba(108,196,255,.25),inset 0 3px 0 var(--sky)}
.yes{color:var(--sky)}.no{color:rgba(147,163,189,.4)}
.yes svg,.no svg{width:18px;height:18px}
.cmp-cta .btn{height:40px;font-size:13px;padding:0 16px}

/* reviews summary */
.rv-grid{display:grid;grid-template-columns:340px 1fr;gap:40px;align-items:start}
.rv-sum{position:sticky;top:100px;padding:30px;border-radius:26px;border:1px solid var(--line);background:linear-gradient(180deg,rgba(11,30,63,.55),var(--ink))}
.rv-sum .big{font-family:var(--serif);font-size:72px;font-weight:800;letter-spacing:-.05em;line-height:1}
.rv-sum .stars{font-size:20px;display:block;margin:8px 0 4px}
.rv-sum small{color:var(--muted)}
.dist{display:grid;gap:9px;margin:24px 0}
.dist div{display:grid;grid-template-columns:34px 1fr 40px;align-items:center;gap:10px;font-size:13px;color:var(--muted)}
.dist .bar{margin:0}
.rv-sum .btn{width:100%}
.rv-cards{display:grid;grid-template-columns:1fr 1fr;gap:16px}
.rv-cards .review{margin:0}
.review .rv-title{font-weight:700;font-size:16px;margin-top:12px}
.review .rv-title + p{margin-top:6px}

/* related */
.related{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}

/* ---------- Sticky add-to-cart ---------- */
.satc{position:fixed;left:50%;bottom:calc(16px + var(--safe-b));z-index:60;width:min(720px,calc(100% - 24px));display:flex;align-items:center;gap:14px;padding:10px 10px 10px 14px;border-radius:22px;
  background:rgba(10,15,26,.9);backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px);border:1px solid rgba(108,196,255,.22);box-shadow:0 24px 60px -12px #000;
  transform:translate(-50%,150%);transition:transform .5s cubic-bezier(.2,.8,.2,1)}
.satc.show{transform:translate(-50%,0)}
.satc .mini{flex:none;width:34px;height:50px;border-radius:2px 5px 5px 2px;background:linear-gradient(150deg,var(--c1),var(--c2));box-shadow:0 0 0 1px rgba(108,196,255,.25)}
.satc .s-info{flex:1;min-width:0;line-height:1.3}
.satc .s-info b{display:block;font-size:14.5px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.satc .s-info small{font-size:13px;color:var(--muted)}
.satc .s-info small strong{color:var(--white)}
.satc .btn{height:48px;padding:0 24px}

/* ---------- Cart drawer ---------- */
.drawer-bg{position:fixed;inset:0;z-index:90;background:rgba(2,4,8,.6);backdrop-filter:blur(4px);-webkit-backdrop-filter:blur(4px);opacity:0;visibility:hidden;transition:.35s}
.drawer{position:fixed;top:0;right:0;bottom:0;z-index:91;width:min(440px,100%);display:flex;flex-direction:column;background:#070b14;border-left:1px solid var(--line);
  transform:translateX(100%);transition:transform .5s cubic-bezier(.2,.8,.2,1);padding-bottom:var(--safe-b)}
.cart-open .drawer-bg{opacity:1;visibility:visible}
.cart-open .drawer{transform:none}
body.cart-open{overflow:hidden}
.dr-head{display:flex;align-items:center;justify-content:space-between;padding:20px 22px;border-bottom:1px solid var(--line)}
.dr-head h3{font-family:var(--serif);font-size:22px;font-weight:800;letter-spacing:-.03em}
.dr-head h3 small{font-family:var(--sans);font-size:13px;color:var(--muted);font-weight:600;letter-spacing:0;margin-left:6px}
.dr-x{width:40px;height:40px;border-radius:12px;border:1px solid var(--line);display:grid;place-items:center;font-size:20px}
.ship-prog{padding:16px 22px;border-bottom:1px solid var(--line);font-size:13.5px}
.ship-prog b{color:var(--sky)}
.ship-prog .bar{margin-top:10px}
.dr-body{flex:1;overflow-y:auto;padding:8px 22px}
.dr-item{display:grid;grid-template-columns:56px 1fr auto;gap:14px;align-items:center;padding:16px 0;border-bottom:1px solid var(--line)}
.dr-item .mini{width:44px;height:64px;margin:0 auto;border-radius:2px 5px 5px 2px;background:linear-gradient(150deg,var(--c1),var(--c2));box-shadow:0 8px 16px -6px #000,0 0 0 1px rgba(108,196,255,.2)}
.dr-item b{display:block;font-size:14.5px}
.dr-item small{color:var(--muted);font-size:12.5px}
.dr-item .qty{height:36px;margin-top:8px;width:max-content}
.dr-item .qty button{width:34px;font-size:16px}
.dr-item .dr-price{text-align:right;font-weight:800}
.dr-item .rm{display:block;margin-top:8px;font-size:12px;color:var(--muted);text-decoration:underline;text-underline-offset:3px;margin-left:auto}
.dr-empty{text-align:center;padding:60px 10px;color:var(--muted)}
.dr-empty .mini{width:54px;height:78px;margin:0 auto 18px;border-radius:2px 6px 6px 2px;background:linear-gradient(150deg,#0b1e3f,#05070b);border:1px dashed rgba(108,196,255,.35)}
.dr-empty .btn{margin-top:20px}
.dr-foot{padding:18px 22px 22px;border-top:1px solid var(--line);background:#05070b}
.dr-line{display:flex;justify-content:space-between;font-size:14px;color:var(--muted);margin-bottom:6px}
.dr-total{display:flex;justify-content:space-between;font-size:18px;font-weight:800;margin:10px 0 16px}
.dr-foot .btn{width:100%;height:56px}
.dr-foot .note{text-align:center;font-size:12px;color:var(--muted);margin-top:12px}
.ref-box{text-align:center;padding:30px 4px}
.ref-box .ic{width:56px;height:56px;border-radius:18px;margin:0 auto 18px}
.ref-box .ic svg{width:26px;height:26px}
.ref-box h4{font-family:var(--serif);font-size:24px;font-weight:800;letter-spacing:-.03em}
.ref-box p{color:var(--muted);font-size:14px;margin:8px 0 20px}
.ref-code{display:flex;align-items:center;justify-content:space-between;gap:10px;padding:8px 8px 8px 18px;border-radius:16px;border:1px dashed rgba(108,196,255,.5);background:var(--sky-soft);font-family:ui-monospace,Consolas,monospace;font-size:18px;font-weight:700;letter-spacing:.06em}
.ref-code .btn{height:40px;font-family:var(--sans);letter-spacing:0}
.ref-box ol{text-align:left;margin:22px 0 0;padding-left:20px;color:#c3cfe3;font-size:14px;display:grid;gap:6px}

/* add-to-cart feedback */
.btn.added{background:#4ade80!important;color:#05210f!important}

/* ---------- Responsive ---------- */
@media (max-width:1024px){
  .pd-grid{grid-template-columns:minmax(0,1fr);gap:28px}
  .gallery{position:static}
  .inside{grid-template-columns:1fr 1fr}
  .highlight{grid-template-columns:1fr;gap:32px}
  .rv-grid{grid-template-columns:1fr}
  .rv-sum{position:static}
  .related{grid-template-columns:1fr 1fr}
}
@media (max-width:640px){
  .crumbs{padding-top:14px;font-size:12px}
  .pd{padding:14px 0 60px}
  .g-main{border-radius:22px;margin-inline:-4px}
  .g-track{aspect-ratio:1/1.05}
  .g-nav,.g-thumbs{display:none}
  .g-dots{display:flex}
  .pbook{width:52%}
  .pback{width:50%}
  .spread{width:86%}
  .info h1{font-size:clamp(34px,10vw,44px);margin-top:14px}
  .price-now{font-size:36px}
  .editions{gap:8px}
  .ed{padding:14px 4px 12px}
  .ed b{font-size:12.5px}
  .bundle{padding:14px}
  .buy{grid-template-columns:auto 1fr}
  .qty button{width:40px}
  .perks{gap:8px}
  .perk{font-size:11.5px;padding:12px 4px}
  .inside{grid-template-columns:1fr;gap:12px}
  .lesson{padding:22px;display:grid;grid-template-columns:auto 1fr;column-gap:18px;align-items:start}
  .lesson .n{font-size:44px;grid-row:span 2}
  .lesson h3{margin:4px 0 4px}
  .hl-visual{border-radius:24px}
  .compare{border-radius:20px}
  .cmp-row{grid-template-columns:84px repeat(3,minmax(0,1fr))}
  .cmp-row>*{padding:13px 5px;font-size:12px;line-height:1.3}
  .cmp-row>:first-child{padding-left:12px;font-size:11.5px}
  .cmp-head>*{padding:18px 4px;gap:8px}
  .cmp-head b{font-size:12.5px}
  .cmp-head .mini{width:26px;height:38px}
  .cmp-cta .btn{padding:0 12px;font-size:12px;height:34px}
  .cmp-cta .ib{font-size:10.5px;padding:5px 8px;white-space:nowrap}
  .rv-cards{grid-template-columns:1fr}
  .rv-sum{padding:24px}
  .related{display:flex;overflow-x:auto;scroll-snap-type:x mandatory;gap:14px;margin-inline:-16px;padding:4px 16px 8px;scrollbar-width:none}
  .related::-webkit-scrollbar{display:none}
  .related .card{flex:0 0 78%;scroll-snap-align:center}
  .satc{bottom:calc(10px + var(--safe-b));width:calc(100% - 20px);border-radius:20px}
  .satc .btn{padding:0 18px}
  footer{padding-bottom:calc(110px + var(--safe-b))}
}
@media (prefers-reduced-motion:reduce){
  .buy .btn-primary::after{display:none}
}