/* TWAO, shared styles */
@view-transition{navigation:auto}
/* page to page: the menu bar stays put, the page underneath fades through */
.gn{view-transition-name:gn}
::view-transition-group(gn){animation-duration:.5s;animation-timing-function:cubic-bezier(.22,.61,.36,1)}
/* the old page stays fully visible underneath while the new one fades in on top: no flash in between */
::view-transition-old(root){animation:vt-hold .45s linear both}
::view-transition-new(root){animation:vt-in .45s cubic-bezier(.25,.1,.25,1) both}
::view-transition-old(root),::view-transition-new(root){mix-blend-mode:normal}
@keyframes vt-hold{from,to{opacity:1}}
@keyframes vt-in{from{opacity:0}}
@media (prefers-reduced-motion:reduce){::view-transition-group(*),::view-transition-old(*),::view-transition-new(*){animation:none!important}}
@property --g{syntax:"<number>";inherits:false;initial-value:0}
:root{
  --ink:#111110; --ink-2:#6b6a66; --ink-3:#8c8b86;
  --paper:#f6f5f1; --mist:#ecebe6; --night:#050505; --night-2:#121212;
  --on-dark:#f3f3ef; --on-dark-2:#aaa8a3;
  --blue:#111110; --blue-hover:#2a2a28; --link:#111110; --link-dark:#f3f3ef;
  --font:"SF Pro Display","SF Pro Text",-apple-system,BlinkMacSystemFont,"Helvetica Neue",Helvetica,Arial,sans-serif;
  --text:"SF Pro Text","SF Pro Display",-apple-system,BlinkMacSystemFont,"Helvetica Neue",Helvetica,Arial,sans-serif;
  --ease:cubic-bezier(.25,.1,.25,1); --lift:cubic-bezier(.22,.61,.36,1); --morph:cubic-bezier(.66,0,.1,1);
}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:84px;-webkit-text-size-adjust:100%}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--text);font-size:17px;line-height:1.47;letter-spacing:-.022em;-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}
img{display:block;max-width:100%}
a{color:var(--link);text-decoration:none}
a:hover{text-decoration:underline}
:focus-visible{outline:2px solid #5ea2ff;outline-offset:3px;border-radius:6px}
.wrap{max-width:1024px;margin:0 auto;padding:0 22px}

/* ---------- TWAO nav: full width and clear over the top of the page, smoky glass once you scroll ---------- */
.gn{position:fixed;inset:0 0 auto;z-index:40;background:rgba(28,28,30,0);
  box-shadow:inset 0 -1px 0 rgba(255,255,255,0);
  -webkit-backdrop-filter:blur(0) saturate(100%);backdrop-filter:blur(0) saturate(100%);
  transition:background-color .7s var(--lift),-webkit-backdrop-filter .7s var(--lift),backdrop-filter .7s var(--lift),box-shadow .7s var(--lift)}
.gn.compact{background:rgba(28,28,30,.42);-webkit-backdrop-filter:blur(22px) saturate(180%);backdrop-filter:blur(22px) saturate(180%);
  box-shadow:inset 0 -1px 0 rgba(255,255,255,.08)}
.gn.open{background:rgba(6,6,6,1)}
/* over a light page top the bar is clear, so the type turns dark */
.gn.ink .gn-logo img{filter:invert(1)}
.gn.ink .gn-links a{color:rgba(17,17,16,.6)}
.gn.ink .gn-links a:hover,.gn.ink .gn-links a[aria-current="page"]{color:#111110}
.gn.ink .gn-burger i{background:#111}
.gn-bar{display:flex;align-items:center;gap:8px;height:52px;max-width:1024px;margin:0 auto;padding:0 22px}
.gn-logo{display:flex;align-items:center;height:52px;margin-right:auto}
.gn-logo img{width:50px;height:21px;object-fit:contain;transition:opacity .5s var(--lift),filter .5s var(--lift)}
.gn-logo:hover img{opacity:.75}
.gn-links{display:flex;gap:30px;margin:0;padding:0;list-style:none}
.gn-links a{position:relative;display:block;padding:6px 0;font-size:13px;letter-spacing:-.005em;color:rgba(243,243,239,.7);transition:color .4s var(--lift)}
.gn-links a::after{content:"";position:absolute;left:0;right:0;bottom:0;height:1px;background:currentColor;transform:scaleX(0);transform-origin:left;transition:transform .5s var(--lift)}
.gn-links a:hover{color:#fff;text-decoration:none}
.gn-links a:hover::after,.gn-links a[aria-current="page"]::after{transform:none}
.gn-links a[aria-current="page"]{color:#fff}
.gn-burger{display:none;appearance:none;background:none;border:0;width:44px;height:44px;margin-right:-12px;cursor:pointer;position:relative;border-radius:50%}
.gn-burger i{position:absolute;left:14px;width:16px;height:1.5px;border-radius:2px;background:#f3f3ef;transition:transform .45s var(--morph),top .45s var(--morph)}
.gn-burger i:first-child{top:18px}.gn-burger i:last-child{top:25px}
.gn.open .gn-burger i:first-child{top:21.5px;transform:rotate(45deg)}
.gn.open .gn-burger i:last-child{top:21.5px;transform:rotate(-45deg)}
.gn-sheet{display:grid;grid-template-rows:0fr;transition:grid-template-rows .55s var(--morph)}
.gn-sheet > div{overflow:hidden;padding:0 22px}
.gn-sheet a{display:block;color:#f3f3ef;font-family:var(--font);font-size:26px;font-weight:500;letter-spacing:-.03em;padding:8px 0;opacity:0;transform:translateY(-6px);transition:opacity .35s var(--ease),transform .45s var(--ease)}
.gn-sheet a:first-child{padding-top:14px}
.gn-sheet a:last-child{padding-bottom:26px}
.gn.open .gn-sheet{grid-template-rows:1fr}
.gn.open .gn-sheet a{opacity:1;transform:none}
.gn.open .gn-sheet a:nth-child(2){transition-delay:.04s}.gn.open .gn-sheet a:nth-child(3){transition-delay:.08s}.gn.open .gn-sheet a:nth-child(4){transition-delay:.12s}.gn.open .gn-sheet a:nth-child(5){transition-delay:.16s}.gn.open .gn-sheet a:nth-child(6){transition-delay:.2s}
@media (min-width:761px){.gn-sheet{display:none}}
@media (max-width:760px){.gn-links{display:none}.gn-burger{display:block}}

/* ---------- Typography ---------- */
/* Section eyebrow: a quiet name above the headline, in sentence case, never a tiny tracked label */
.eyebrow{font-family:var(--font);font-size:clamp(19px,1.75vw,24px);font-weight:600;letter-spacing:.009em;line-height:1.17;color:var(--ink);margin:0 0 14px}
.dark .eyebrow{color:var(--on-dark)}
.eyebrow.new{background:linear-gradient(90deg,#5ea2ff,#bf8cff 60%,#d9a0ff);-webkit-background-clip:text;background-clip:text;color:transparent;display:inline-block}
.eyebrow.new + *{margin-top:0}
.hero .eyebrow{font-size:clamp(21px,2.2vw,28px);margin-bottom:18px}
.h-xl{font-family:var(--font);font-size:clamp(50px,8vw,112px);font-weight:500;letter-spacing:-.06em;line-height:.92;margin:0}
.h-l{font-family:var(--font);font-size:clamp(40px,5.8vw,72px);font-weight:500;letter-spacing:-.05em;line-height:.98;margin:0}
.h-m{font-family:var(--font);font-size:clamp(32px,4.2vw,52px);font-weight:500;letter-spacing:-.045em;line-height:1;margin:0}
.h-s{font-family:var(--font);font-size:clamp(26px,3vw,32px);font-weight:600;letter-spacing:.004em;line-height:1.125;margin:0}
.sub{font-family:var(--font);font-size:clamp(18px,2vw,24px);font-weight:400;letter-spacing:-.02em;line-height:1.3;margin:16px 0 0;color:var(--ink-2)}
.dark .sub{color:var(--on-dark-2)}
.dot{color:#969692}
.body-l{font-size:clamp(17px,1.6vw,21px);line-height:1.38;letter-spacing:.011em;color:var(--ink-2)}
.dark .body-l{color:var(--on-dark-2)}
/* Copy: grey sentence, with the line that matters set in ink */
.body-l b,.body-l strong,.sub b{font-weight:inherit;color:var(--ink)}
.dark .body-l b,.dark .body-l strong,.dark .sub b{color:var(--on-dark)}
.muted{color:var(--ink-2)}
.dark .muted{color:var(--on-dark-2)}
.grad{background:linear-gradient(90deg,#5ea2ff 0%,#bf8cff 50%,#ff9f6b 100%);-webkit-background-clip:text;background-clip:text;color:transparent}

/* ---------- Buttons and links ---------- */
.ctas{display:flex;flex-wrap:wrap;justify-content:center;gap:14px 16px;margin-top:22px}
.btn{display:inline-flex;align-items:center;justify-content:center;font:inherit;font-size:15px;letter-spacing:-.022em;line-height:1;border-radius:999px;padding:14px 24px;min-width:28px;cursor:pointer;border:1px solid transparent;transition:background-color .5s var(--lift),color .5s var(--lift),border-color .5s var(--lift),transform .5s var(--lift)}
.btn:hover{transform:translateY(-2px)}
.btn:hover{text-decoration:none}
.btn:active{transform:scale(.97);transition-duration:.15s}
.btn-blue{background:var(--ink);color:#f3f3ef}
.btn-blue:hover{background:#2a2a28}
.btn-line{background:transparent;color:var(--ink);border-color:rgba(17,17,16,.25)}
.btn-line:hover{border-color:var(--ink)}
.dark .btn-blue{background:#f3f3ef;color:#050505}
.dark .btn-blue:hover{background:#fff}
.dark .btn-line{color:#f3f3ef;border-color:rgba(255,255,255,.28);background:rgba(255,255,255,.04);backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px)}
.dark .btn-line:hover{border-color:#fff}
.btn-sm{font-size:14px;padding:8px 16px}
.more-link{font-size:17px;display:inline-flex;align-items:center;gap:4px}
.more-link::after{content:"";width:6px;height:6px;border-right:1.4px solid currentColor;border-top:1.4px solid currentColor;rotate:45deg;margin-left:3px;transition:translate .5s var(--lift)}
.more-link:hover::after{translate:2px 0}
.dark a{color:var(--link-dark)}
.dark a.tb,a.tb{color:var(--on-dark)}
.dark a.tb .go{color:#f3f3ef}
.tbs{text-align:left}

/* ---------- Sections ---------- */
.dark{background:var(--night);color:var(--on-dark)}
.mist{background:var(--mist)}
.sec{padding:clamp(72px,10vw,120px) 0}
.center{text-align:center}

/* Ambient light (from the TWAO home page) */
.ambient{position:absolute;inset:0;overflow:hidden;pointer-events:none;z-index:0}
.orb{position:absolute;border-radius:50%;filter:blur(100px);mix-blend-mode:screen}
.orb-a{width:55vw;height:55vw;left:-20vw;top:10%;background:rgba(35,100,160,.34);animation:drift 13s ease-in-out infinite alternate}
.orb-b{width:48vw;height:48vw;right:-15vw;top:-20%;background:rgba(165,95,60,.26);animation:drift-r 17s ease-in-out infinite alternate}
.orb-c{width:40vw;height:40vw;right:15vw;bottom:-30%;background:rgba(103,59,150,.3);animation:drift 15s ease-in-out infinite alternate-reverse}
@keyframes drift{to{transform:translate(13vw,-7vh) scale(1.15)}}
@keyframes drift-r{to{transform:translate(-12vw,11vh) scale(1.12)}}
.lit{position:relative;overflow:hidden;overflow:clip;isolation:isolate}
.lit > :not(.ambient){position:relative;z-index:1}

/* ---------- Liquid glass ---------- */
.glass{position:relative;isolation:isolate;border-radius:28px;
  background:radial-gradient(340px circle at var(--mx,30%) var(--my,0%),rgba(255,255,255,calc(.10*var(--g))),transparent 62%),
             radial-gradient(120% 85% at 14% 0%,rgba(255,255,255,.16),rgba(255,255,255,.05) 45%,rgba(255,255,255,.03));
  backdrop-filter:blur(22px) saturate(190%) brightness(1.08);-webkit-backdrop-filter:blur(22px) saturate(190%) brightness(1.08);
  box-shadow:inset 0 1px 0 rgba(255,255,255,.32),inset 0 -1px 0 rgba(255,255,255,.05),inset 0 0 28px rgba(255,255,255,.035),0 24px 60px -26px rgba(0,0,0,.55)}
.glass::after{content:"";position:absolute;inset:0;border-radius:inherit;pointer-events:none;padding:1px;
  background:linear-gradient(140deg,rgba(255,255,255,.55),rgba(255,255,255,.14) 28%,rgba(255,255,255,.05) 55%,rgba(255,255,255,.22) 100%);
  -webkit-mask:linear-gradient(#000 0 0) content-box,linear-gradient(#000 0 0);-webkit-mask-composite:xor;mask:linear-gradient(#000 0 0) content-box exclude,linear-gradient(#000 0 0);
  opacity:.7;transition:opacity .7s var(--lift)}

/* textbook tiles */
.tbs{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:20px}
.tb{display:flex;flex-direction:column;min-height:280px;padding:32px 30px 28px;color:var(--on-dark);text-decoration:none;transform:translateZ(0);transition:transform .7s var(--lift),--g .7s var(--lift)}
.tb:hover{text-decoration:none}
.tb::before{content:"";position:absolute;inset:0;border-radius:inherit;z-index:-2;box-shadow:0 34px 80px -22px rgba(0,0,0,.7),0 12px 28px -14px rgba(0,0,0,.55);opacity:0;transition:opacity .7s var(--lift)}
.tb .subj{font-family:var(--font);font-size:15px;font-weight:600;letter-spacing:-.01em;color:var(--on-dark-2);margin:0}
.tb h3{font-family:var(--font);font-size:28px;font-weight:500;letter-spacing:-.035em;line-height:1.06;margin:12px 0 12px;text-wrap:balance}
.tb p{margin:0;color:var(--on-dark-2);font-size:15px;line-height:1.5;letter-spacing:-.01em}
.tb .go{margin-top:auto;padding-top:26px;color:#f3f3ef;font-size:15px;display:inline-flex;align-items:center;gap:4px}
.tb .go::after{content:"";width:6px;height:6px;border-right:1.4px solid currentColor;border-top:1.4px solid currentColor;rotate:45deg;margin-left:3px;transition:translate .5s var(--lift)}
@media (hover:hover) and (pointer:fine){
  .tb:hover{transform:translateY(-6px) scale(1.012);--g:1}
  .tb:hover::before,.tb:hover::after{opacity:1}
  .tb:hover .go::after{translate:3px 0}
}
.tb:active{transform:scale(.985);transition-duration:.25s}

/* ---------- Reveal ---------- */
/* Reveal runs as an animation, not a transition, so it never overrides an element's own hover transitions */
.js [data-reveal]{opacity:0}
.js [data-reveal].in{animation:reveal-in .9s var(--ease) var(--d,0ms) both}
@keyframes reveal-in{from{opacity:0;translate:0 30px}to{opacity:1;translate:0 0}}
@keyframes rise{from{opacity:0;transform:translateY(30px)}to{opacity:1;transform:none}}
.rise{animation:rise .9s var(--ease) both}
.rise-1{animation-delay:.1s}.rise-2{animation-delay:.25s}.rise-3{animation-delay:.4s}.rise-4{animation-delay:.55s}

/* ---------- Footer ---------- */
.ft{background:var(--mist);color:var(--ink-2);font-size:12px;line-height:1.33;letter-spacing:-.01em;padding:18px 0 40px}
.ft p{margin:0 0 10px;max-width:980px}
.ft .row{display:flex;flex-wrap:wrap;justify-content:space-between;gap:10px;border-top:1px solid #d9d8d2;padding-top:14px;margin-top:14px}
.ft a{color:#3a3a37}
.ft details summary{cursor:pointer;color:#3a3a37;list-style:none;display:inline-block;margin:0 0 10px}
.ft details summary::-webkit-details-marker{display:none}
.ft details[open] summary{margin-bottom:6px}

@media (max-width:833px){.tbs{grid-template-columns:repeat(2,minmax(0,1fr))}}
@media (max-width:600px){
  .wrap{padding:0 16px}
  .h-xl{font-size:clamp(40px,12vw,54px);letter-spacing:-.055em}
  .h-l{font-size:clamp(34px,10vw,44px)}
  .tbs{grid-template-columns:minmax(0,1fr);gap:14px}
  .tb{min-height:0;padding:28px 24px 24px}
  .btn{font-size:15px;padding:11px 20px}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation:none!important;transition:none!important}
  .js [data-reveal]{opacity:1;translate:none}
}

/* ---------- Sheets (light modals) ---------- */
.sheet[hidden]{display:none}
.sheet{position:fixed;inset:0;z-index:60;display:grid;place-items:center;padding:20px}
.sheet-bg{position:absolute;inset:0;background:rgba(0,0,0,.48);backdrop-filter:blur(8px);-webkit-backdrop-filter:blur(8px);opacity:0;transition:opacity .4s var(--ease)}
.sheet.open .sheet-bg{opacity:1}
.sheet-card{position:relative;width:min(680px,100%);max-height:88svh;overflow:auto;background:#fbfaf7;color:var(--ink);border-radius:28px;padding:56px clamp(26px,6vw,64px) 52px;box-shadow:0 40px 120px rgba(0,0,0,.35);opacity:0;transform:translateY(24px) scale(.96);transition:opacity .45s var(--ease),transform .55s cubic-bezier(.22,.8,.24,1)}
.sheet.open .sheet-card{opacity:1;transform:none}
.sheet .close{position:absolute;top:16px;right:16px;width:36px;height:36px;border-radius:50%;border:0;background:#ecebe6;color:#3a3a37;font-size:20px;line-height:1;cursor:pointer;transition:background-color .45s var(--lift),transform .45s var(--lift)}
.sheet .close:hover{transform:rotate(90deg)}
.sheet .close:hover{background:#e2e1db}
.sheet .eyebrow{color:var(--ink-2);font-size:17px;margin:0 0 8px}
.sheet h2{font-family:var(--font);font-size:clamp(30px,4vw,42px);font-weight:500;letter-spacing:-.045em;line-height:1.02;margin:0 0 20px}
.sheet p{margin:0;color:#4a4945;font-size:17px;line-height:1.53}
.sheet .pts{list-style:none;margin:24px 0;padding:22px 0;border-top:1px solid #e4e3dd;border-bottom:1px solid #e4e3dd;display:grid;gap:12px}
.sheet .pts li{color:#4a4945;font-size:17px;line-height:1.5}
.sheet .pts b{color:var(--ink);font-weight:600}
body.sheet-open{overflow:hidden}
.sheet .sheet-backdrop{position:absolute;inset:0;background:rgba(0,0,0,.48);backdrop-filter:blur(8px);-webkit-backdrop-filter:blur(8px);opacity:0;transition:opacity .4s var(--ease)}
.sheet.open .sheet-backdrop{opacity:1}
@media (max-width:600px){
  .sheet{padding:0;place-items:end center}
  .sheet-card{border-radius:28px 28px 0 0;transform:translateY(60px)}
}

/* ---------- Textbook Request form (inside a light sheet) ---------- */
.kicker,.sheet .kicker{font-family:var(--font);font-size:15px;font-weight:600;letter-spacing:-.01em;color:var(--ink-2);margin:0}
.req-card{padding:0!important;display:flex;flex-direction:column;width:min(640px,100%)}
.sheet-head{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:22px 26px 0}
.sheet-head .close{position:static}
.steps{display:flex;gap:6px;align-items:center}
.steps i{width:22px;height:4px;border-radius:4px;background:#ecebe6;transition:background-color .5s var(--lift),width .5s var(--lift)}
.steps i.on{background:var(--ink);width:36px}
.steps i.done{background:#bdbcb6}
.sheet-body{position:relative;overflow:hidden auto;padding:6px 26px 4px}
.pane{padding:12px 0 6px}
.pane[hidden]{display:none}
.pane h3{font-family:var(--font);font-size:clamp(26px,3.4vw,34px);font-weight:500;letter-spacing:-.04em;line-height:1.05;margin:6px 0 8px;color:var(--ink)}
.pane .sub{font-family:var(--text);color:var(--ink-2);font-size:15px;line-height:1.5;margin:0 0 22px;letter-spacing:-.01em}
.field{display:grid;gap:7px;margin:0 0 16px}
.field label,.field .lab{font-size:13px;color:var(--ink-2)}
.field label b{color:var(--ink);font-weight:500}
.row2{display:grid;grid-template-columns:1fr 1fr;gap:0 14px}
.inp{font:inherit;font-size:17px;color:var(--ink);background:#fff;border:1px solid #d9d8d2;border-radius:12px;padding:13px 14px;width:100%;transition:border-color .45s var(--lift),box-shadow .45s var(--lift)}
.inp::placeholder{color:#a1a1a6}
.inp:focus{outline:none;border-color:var(--ink);box-shadow:0 0 0 4px rgba(17,17,16,.08)}
textarea.inp{min-height:100px;resize:vertical;line-height:1.45}
.inp.bad{border-color:#e30000;box-shadow:0 0 0 4px rgba(227,0,0,.08)}
.hint{font-size:12px;color:var(--ink-3);line-height:1.45}
.err{font-size:12px;color:#e30000}
.chips{display:flex;flex-wrap:wrap;gap:8px}
.chip{appearance:none;font:inherit;font-size:14px;cursor:pointer;color:var(--ink);background:#fff;border:1px solid #d9d8d2;border-radius:980px;padding:9px 15px;transition:background-color .45s var(--lift),border-color .45s var(--lift),color .45s var(--lift),transform .45s var(--lift)}
.chip:hover{border-color:#86868b}
.chip[aria-pressed="true"]{background:var(--ink);border-color:var(--ink);color:#fff}
.chip:active{transform:scale(.96)}
.check{display:grid;grid-template-columns:22px 1fr;gap:10px;align-items:start;font-size:14px;color:#424245;line-height:1.45;margin:0 0 12px;cursor:pointer}
.check input{appearance:none;width:20px;height:20px;margin:0;border:1.5px solid #86868b;border-radius:6px;display:grid;place-items:center;cursor:pointer;transition:background-color .35s var(--lift),border-color .35s var(--lift)}
.check input::after{content:"";width:9px;height:5px;border-left:2px solid #fff;border-bottom:2px solid #fff;rotate:-45deg;translate:0 -1px;opacity:0;transition:opacity .2s}
.check input:checked{background:var(--ink);border-color:var(--ink)}
.check input:checked::after{opacity:1}
.check.bad input{border-color:#e30000}
.hp{position:absolute;left:-9999px;width:1px;height:1px;opacity:0}
.sheet-foot{display:flex;justify-content:space-between;align-items:center;gap:12px;padding:16px 26px 22px;border-top:1px solid #ecebe6}
.sheet-foot .acts{display:flex;gap:10px}
.btn-primary{background:var(--blue);color:#fff;font-size:15px;padding:11px 20px}
.btn-primary:hover{background:var(--blue-hover)}
.btn-ghost{background:#fff;color:var(--ink);border-color:#d9d8d2;font-size:15px;padding:11px 20px}
.btn-ghost:hover{border-color:var(--ink)}
.btn[disabled]{opacity:.45;cursor:default}
.done-view{text-align:center;padding:26px 6px 18px}
.done-mark{width:68px;height:68px;margin:6px auto 22px;border-radius:50%;background:#e8f8ec;display:grid;place-items:center}
.done-mark svg{width:30px;height:30px}
.done-mark path{stroke:#1d9b46;stroke-width:2.4;fill:none;stroke-linecap:round;stroke-linejoin:round;stroke-dasharray:40;stroke-dashoffset:40}
.done-view.play .done-mark path{transition:stroke-dashoffset .7s cubic-bezier(.65,0,.35,1) .25s;stroke-dashoffset:0}
.done-view .ref{display:inline-block;margin-top:16px;font-size:13px;color:var(--ink-3);letter-spacing:-.01em}
@media (max-width:600px){.row2{grid-template-columns:minmax(0,1fr)}.sheet-head,.sheet-body,.sheet-foot{padding-left:20px;padding-right:20px}}

/* ---------- Read more (Book preview) ---------- */
.more summary{list-style:none;cursor:pointer;display:inline-flex;align-items:center;gap:10px;margin-top:6px;border-radius:980px;padding:12px 16px 12px 20px;font-size:14px;background:var(--ink);color:#f3f3ef;transition:background-color .5s var(--lift),transform .5s var(--lift)}
.more summary::-webkit-details-marker{display:none}
.more summary:hover{background:#2a2a28}
.more summary:active{transform:scale(.97)}
.more .label{display:grid;overflow:hidden}
.more .label span{grid-area:1/1;transition:opacity .3s ease-out,transform .3s ease-out}
.more .label .opened{opacity:0;transform:translateY(70%) scale(.8)}
.more.is-open .label .closed{opacity:0;transform:translateY(-70%) scale(.8)}
.more.is-open .label .opened{opacity:1;transform:none;transition-delay:.12s}
.more:not(.is-open) .label .closed{transition-delay:.12s}
.more .icon{position:relative;width:12px;height:12px;flex:none;transition:transform .5s var(--morph)}
.more .icon::before,.more .icon::after{content:"";position:absolute;left:50%;top:50%;width:11px;height:1.6px;border-radius:2px;background:currentColor;translate:-50% -50%}
.more .icon::after{rotate:90deg}
.more.is-open .icon{transform:rotate(135deg)}
.more .full{overflow:hidden}
.more .full-inner{padding-top:24px}
.more .full p{transition:opacity .2s ease-out,transform .3s ease-out}
.more.is-collapsed .full p{opacity:0;transform:translateY(-8px)}
.more.is-entering .full p{opacity:0;transform:translateY(24px);transition:none}

/* request: file drop */
.drop{position:relative;border:1.5px dashed #c9c8c1;border-radius:16px;background:#fff;transition:border-color .45s var(--lift),background-color .45s var(--lift),box-shadow .45s var(--lift)}
.drop input[type=file]{position:absolute;width:1px;height:1px;opacity:0;pointer-events:none}
.drop-btn{appearance:none;font:inherit;color:var(--ink);background:none;border:0;width:100%;padding:22px 16px 20px;display:grid;justify-items:center;gap:4px;cursor:pointer;border-radius:15px;text-align:center}
.drop-btn svg{color:var(--ink-2);margin-bottom:4px;transition:transform .6s var(--lift)}
.drop-btn b{font-weight:500;font-size:16px}
.drop-or{font-size:14px;color:var(--ink-2)}
.drop-hint{font-size:12px;color:var(--ink-3);margin-top:6px;line-height:1.4}
.drop:hover{border-color:#86868b}
.drop:hover .drop-btn svg{transform:translateY(-2px)}
.drop-btn:focus-visible{outline:none;box-shadow:0 0 0 4px rgba(17,17,16,.1)}
.drop.over{border-color:var(--ink);background:#f6f5f1;box-shadow:0 0 0 4px rgba(17,17,16,.06)}
.drop.over .drop-btn svg{transform:translateY(-4px)}
.drop.bad{border-color:#e30000}
.files{list-style:none;margin:10px 0 0;padding:0;display:grid;gap:8px}
.files:empty{margin:0}
.files li{position:relative;display:grid;grid-template-columns:38px minmax(0,1fr) auto 28px;align-items:center;gap:10px;background:#fff;border:1px solid #e3e2dc;border-radius:12px;padding:9px 8px 9px 10px;overflow:hidden}
.fi-ic{width:38px;height:38px;border-radius:8px;background:var(--mist);display:grid;place-items:center;font-size:9.5px;font-weight:600;letter-spacing:.04em;color:var(--ink-2)}
.fi-n{font-size:14px;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.fi-s{font-size:12px;color:var(--ink-3);font-variant-numeric:tabular-nums}
.fi-x{appearance:none;border:0;background:none;width:28px;height:28px;border-radius:50%;font-size:19px;line-height:1;color:var(--ink-3);cursor:pointer;transition:background-color .35s var(--lift),color .35s var(--lift)}
.fi-x:hover{background:var(--mist);color:var(--ink)}
.fi-bar{position:absolute;left:0;right:0;bottom:0;height:2px;opacity:0;transition:opacity .4s}
.fi-bar b{display:block;height:100%;background:var(--ink);transform:scaleX(0);transform-origin:left;transition:transform .3s linear}
.files li.up .fi-bar{opacity:1}
.files li.ok .fi-bar{opacity:0}
.files li.up .fi-x{visibility:hidden}
.files li.ok .fi-x{visibility:visible;pointer-events:none;color:var(--ink);font-size:0}
.files li.ok .fi-x::after{content:"";display:inline-block;width:10px;height:5px;border-left:1.8px solid currentColor;border-bottom:1.8px solid currentColor;rotate:-45deg;translate:0 -2px}
@media (hover:none){.drop-or{display:none}}

/* footer: site links and language */
.ft-links{display:flex;flex-wrap:wrap;gap:6px 18px}
.ft-links a{color:#3a3a37}
.ft-lang{display:inline-flex;gap:2px;margin-top:16px;padding:3px;border-radius:999px;background:rgba(17,17,16,.06)}
.ft-lang a{font-size:12px;padding:6px 13px;border-radius:999px;color:var(--ink-2);text-decoration:none;transition:background-color .4s var(--lift),color .4s var(--lift)}
.ft-lang a:hover{color:var(--ink);text-decoration:none}
.ft-lang a[aria-current="true"]{background:#fff;color:var(--ink);box-shadow:0 1px 2px rgba(0,0,0,.08)}
.check a{color:var(--ink);text-decoration:underline;text-decoration-color:rgba(17,17,16,.3);text-underline-offset:2px}
.sheet .ctas{justify-content:flex-start;margin-top:28px}

/* Textbooks: coming soon shelf */
.shelf{display:flex;justify-content:center;align-items:flex-end;gap:12px;height:300px;position:relative}
.shelf::before{content:"";position:absolute;left:50%;bottom:-40px;width:min(560px,90%);height:90px;translate:-50% 0;border-radius:50%;background:radial-gradient(closest-side,rgba(150,180,255,.10),transparent);filter:blur(6px);pointer-events:none}
.shelf::after{content:"";position:absolute;left:50%;bottom:0;width:min(640px,92%);height:1px;translate:-50% 0;background:linear-gradient(90deg,transparent,rgba(255,255,255,.28) 30%,rgba(255,255,255,.42) 50%,rgba(255,255,255,.28) 70%,transparent)}
.spine{width:58px;height:var(--h);border-radius:9px 9px 4px 4px;overflow:hidden;flex:none;transition:transform .8s var(--lift)}
/* one soft light travels across the whole shelf: each spine catches it a moment after its neighbour */
.spine::before{content:"";position:absolute;inset:-10% -60%;pointer-events:none;mix-blend-mode:screen;
  background:linear-gradient(112deg,transparent 38%,rgba(255,255,255,.04) 44%,rgba(255,255,255,.16) 48.5%,rgba(255,255,255,.3) 50%,rgba(255,255,255,.16) 51.5%,rgba(255,255,255,.04) 56%,transparent 62%);
  transform:translateX(-70%);animation:sheen 9s cubic-bezier(.45,.05,.25,1) infinite;animation-delay:calc(var(--n)*.16s + 1s)}
@keyframes sheen{0%{transform:translateX(-70%)}20%,100%{transform:translateX(70%)}}
/* a brief glint on the top edge as the light passes */
.spine b{position:absolute;left:12%;right:12%;top:0;height:1px;background:linear-gradient(90deg,transparent,rgba(255,255,255,.95),transparent);opacity:0;animation:glint 9s ease-out infinite;animation-delay:calc(var(--n)*.16s + 1.6s)}
@keyframes glint{0%{opacity:0}3%{opacity:.9}12%,100%{opacity:0}}
.spine i{position:absolute;left:14px;right:14px;height:1px;background:rgba(255,255,255,.16)}
.spine i:nth-child(1){top:22px}.spine i:nth-child(2){top:27px}.spine i:nth-child(3){bottom:22px}
.spine.lean{rotate:-6deg;transform-origin:bottom left;margin-left:16px}
@media (hover:hover) and (pointer:fine){.spine:hover{transform:translateY(-12px)}}
.shelf-note{text-align:center}
.pill{display:inline-flex;align-items:center;gap:8px;margin-top:34px;padding:9px 16px;border-radius:999px;font-size:14px;color:var(--on-dark);background:rgba(255,255,255,.07);box-shadow:inset 0 0 0 1px rgba(255,255,255,.14)}
.pill b{width:7px;height:7px;border-radius:50%;background:#5ea2ff;box-shadow:0 0 12px #5ea2ff;animation:pulse 2.4s ease-in-out infinite}
@keyframes pulse{50%{opacity:.35}}
@media (max-width:600px){.shelf{gap:8px;height:240px}.spine{width:36px;height:calc(var(--h)*.8)}.spine i{left:9px;right:9px}}
@media (prefers-reduced-motion:reduce){.spine::before,.spine b,.pill b{animation:none}.spine::before{transform:translateX(-70%)}}