/* USOrgo — notebook look to match the PDFs: dot-grid paper, sticky notes, rainbow strip.
   Colours follow the curly-arrow convention used inside the products:
   blue = nucleophile (primary), red = electrophile (accent), green = leaving group / success. */
:root{
  --bg:#fbfbfe; --paper:#ffffff; --sunk:#f1f3fb; --ink:#23263a; --muted:#5b6078; --line:#dfe3f1;
  --blue:#1d4ed8; --blue-ink:#ffffff; --blue-soft:#e6edff;
  --red:#c92a2a; --red-soft:#ffe9e7;
  --green:#15803d; --green-soft:#dff6e7;
  --sticky:#fff1a8; --sticky-ink:#3d3300;
  --dot:#d9ddef;
  --shadow:0 1px 0 rgba(35,38,58,.05),0 10px 30px -12px rgba(35,38,58,.18);
  --hand:"Caveat","Segoe Print","Bradley Hand",cursive;
  --body:Inter,system-ui,-apple-system,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  --r:16px;
}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){
  --bg:#12141f; --paper:#1a1d2c; --sunk:#202437; --ink:#eceef8; --muted:#a3a9c4; --line:#2c3150;
  --blue:#7ea2ff; --blue-ink:#0d1330; --blue-soft:#1f2850;
  --red:#ff8a80; --red-soft:#3a2125;
  --green:#5fd68a; --green-soft:#16301f;
  --sticky:#4a4116; --sticky-ink:#fff3b0; --dot:#252a42; color-scheme:dark}}
:root[data-theme="dark"]{
  --bg:#12141f; --paper:#1a1d2c; --sunk:#202437; --ink:#eceef8; --muted:#a3a9c4; --line:#2c3150;
  --blue:#7ea2ff; --blue-ink:#0d1330; --blue-soft:#1f2850;
  --red:#ff8a80; --red-soft:#3a2125;
  --green:#5fd68a; --green-soft:#16301f;
  --sticky:#4a4116; --sticky-ink:#fff3b0; --dot:#252a42; color-scheme:dark}

*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.6 var(--body);
  background-image:radial-gradient(var(--dot) 1px,transparent 1.2px);background-size:22px 22px;
  -webkit-font-smoothing:antialiased}
body::before{content:"";position:fixed;inset:0 0 auto 0;height:6px;z-index:60;
  background:linear-gradient(90deg,#ff9e80,#ffd54f,#81d98f,#6ec6ff,#a78bfa)}
a{color:var(--blue)}
img{max-width:100%;display:block}
.wrap{max-width:1080px;margin:0 auto;padding:0 20px}
.hand{font-family:var(--hand);font-weight:700}
h1,h2,h3{line-height:1.15;margin:0 0 .5em;letter-spacing:-.01em}
h1{font-size:clamp(2.2rem,5.4vw,3.6rem);font-weight:800}
h2{font-size:clamp(1.6rem,3.4vw,2.2rem);font-weight:800}
h3{font-size:1.15rem;font-weight:700}
p{margin:0 0 1em}
.muted{color:var(--muted)}
section{padding:72px 0}
.eyebrow{font-family:var(--hand);font-size:1.5rem;color:var(--red);margin:0 0 .2em}

/* nav */
.nav{position:sticky;top:6px;z-index:50;background:color-mix(in srgb,var(--bg) 88%,transparent);
  backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
.nav .wrap{display:flex;align-items:center;gap:20px;height:60px}
.logo{font-family:var(--hand);font-size:2rem;font-weight:700;color:var(--ink);text-decoration:none;line-height:1}
.logo b{color:var(--blue)}
.nav nav{margin-left:auto;display:flex;gap:22px;align-items:center}
.nav nav a{color:var(--muted);text-decoration:none;font-weight:500;font-size:.95rem}
.nav nav a:hover{color:var(--ink)}
.icon-btn{border:1px solid var(--line);background:var(--paper);color:var(--ink);border-radius:999px;
  width:38px;height:38px;cursor:pointer;font-size:1rem}
@media(max-width:760px){.nav nav a.hide-m{display:none}}

/* buttons */
.btn{display:inline-flex;align-items:center;gap:8px;border:2px solid var(--blue);background:var(--blue);
  color:var(--blue-ink);font:600 1rem var(--body);padding:12px 22px;border-radius:999px;cursor:pointer;
  text-decoration:none;transition:transform .12s,box-shadow .12s}
.btn:hover{transform:translateY(-1px);box-shadow:0 8px 20px -8px var(--blue)}
.btn.ghost{background:transparent;color:var(--blue)}
.btn:focus-visible,.icon-btn:focus-visible,summary:focus-visible,input:focus-visible,a:focus-visible{outline:3px solid var(--red);outline-offset:2px}

/* hero */
.hero{padding:64px 0 40px}
.hero .grid{display:grid;grid-template-columns:1.15fr .85fr;gap:44px;align-items:center}
@media(max-width:860px){.hero .grid{grid-template-columns:1fr}}
.badge{display:inline-flex;gap:8px;align-items:center;background:var(--green-soft);color:var(--green);
  border:1px solid color-mix(in srgb,var(--green) 40%,transparent);border-radius:999px;padding:5px 14px;
  font-weight:600;font-size:.88rem;margin-bottom:18px}
.hero h1 em{font-style:normal;color:var(--blue);background:linear-gradient(transparent 62%,var(--sticky) 62%)}
.lead{font-size:1.15rem;color:var(--muted);max-width:34em}
.cta-row{display:flex;gap:12px;flex-wrap:wrap;margin:22px 0 14px}
.trust{display:flex;gap:18px;flex-wrap:wrap;font-size:.9rem;color:var(--muted)}
.trust span::before{content:"✓ ";color:var(--green);font-weight:700}
.hero-card{position:relative}
.hero-card img{border-radius:var(--r);border:1px solid var(--line);box-shadow:var(--shadow);transform:rotate(1.6deg)}
.hero-card .note{position:absolute;left:-14px;bottom:-18px;transform:rotate(-3deg);background:var(--sticky);
  color:var(--sticky-ink);font-family:var(--hand);font-size:1.4rem;padding:10px 16px;border-radius:4px;
  box-shadow:var(--shadow);max-width:240px;line-height:1.15}

/* cards */
.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:18px}
.card{background:var(--paper);border:1px solid var(--line);border-radius:var(--r);padding:22px;box-shadow:var(--shadow);position:relative}
.card .tag{position:absolute;top:-11px;right:16px;font-size:.78rem;font-weight:700;padding:3px 10px;border-radius:999px}
.tag.ready{background:var(--green-soft);color:var(--green)}
.tag.soon{background:var(--sunk);color:var(--muted)}
.card .ico{font-size:1.6rem;margin-bottom:8px}

/* sample problem */
.sample{display:grid;grid-template-columns:1fr 1fr;gap:28px;align-items:start}
@media(max-width:860px){.sample{grid-template-columns:1fr}}
.problem{background:var(--paper);border:1px solid var(--line);border-top:6px solid var(--green);
  border-radius:var(--r);padding:22px;box-shadow:var(--shadow)}
.pill{display:inline-block;font-family:var(--hand);font-size:1.2rem;font-weight:700;background:var(--green-soft);
  color:var(--green);border-radius:999px;padding:0 14px;margin-right:6px}
.answer{background:var(--sticky);color:var(--sticky-ink);border-radius:8px;padding:14px 16px;margin:14px 0;display:none}
.answer.show,.steps.show{display:block}
.answer .tagline{font-family:var(--hand);font-size:1.3rem;background:#ff7043;color:#fff;border-radius:999px;padding:0 12px;margin-right:8px}
.steps{display:none;margin:0;padding-left:1.2em}
.steps li{margin:.5em 0}
.try{margin:14px 0 0;display:grid;gap:8px}
.try label{display:flex;gap:10px;align-items:flex-start;padding:10px 12px;border:1px solid var(--line);border-radius:12px;cursor:pointer;background:var(--paper)}
.try input{margin-top:5px}
.try label.ok{border-color:var(--green);background:var(--green-soft)}
.try label.no{border-color:var(--red);background:var(--red-soft)}
.fb{min-height:1.5em;font-weight:600;margin-top:8px}
.molrow{display:flex;gap:18px;flex-wrap:wrap;margin:10px 0}
.molrow figure{margin:0;text-align:center;font-size:.82rem;color:var(--muted)}
.molrow svg{display:block;margin:0 auto 4px;stroke:var(--ink);stroke-width:2.4;fill:none;stroke-linecap:round;stroke-linejoin:round}
.molrow svg text{fill:var(--ink);stroke:none;font:600 15px var(--body)}

/* gallery */
.gallery{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:20px}
.gallery figure{margin:0}
.gallery img{border-radius:12px;border:1px solid var(--line);box-shadow:var(--shadow);background:#fff}
.gallery figcaption{font-size:.88rem;color:var(--muted);margin-top:8px}

/* roadmap */
table{width:100%;border-collapse:collapse;background:var(--paper);border:1px solid var(--line);border-radius:var(--r);overflow:hidden}
th,td{text-align:left;padding:11px 14px;border-bottom:1px solid var(--line);font-size:.95rem}
th{background:var(--sunk);font-weight:700}
tr:last-child td{border-bottom:0}
.st{font-weight:700;font-size:.82rem;padding:2px 10px;border-radius:999px;white-space:nowrap}
.st.ready{background:var(--green-soft);color:var(--green)}
.st.next{background:var(--blue-soft);color:var(--blue)}
.st.later{background:var(--sunk);color:var(--muted)}
.tablewrap{overflow-x:auto;border-radius:var(--r)}

/* steps */
.how{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:18px;counter-reset:s}
.how .card::before{counter-increment:s;content:counter(s);font-family:var(--hand);font-size:2.2rem;color:var(--blue);
  position:absolute;top:8px;right:18px;opacity:.5}

/* pricing */
.plans{display:grid;grid-template-columns:repeat(auto-fit,minmax(260px,1fr));gap:18px;align-items:stretch}
.plan{background:var(--paper);border:1px solid var(--line);border-radius:var(--r);padding:26px;box-shadow:var(--shadow);display:flex;flex-direction:column}
.plan.feat{border:2px solid var(--blue)}
.price{font-size:2.4rem;font-weight:800;margin:.1em 0}
.price s{font-size:1.1rem;color:var(--muted);font-weight:500;margin-left:6px}
.plan ul{padding-left:1.1em;margin:0 0 18px;color:var(--muted);flex:1}
.plan li{margin:.35em 0}
.coupon{background:var(--sticky);color:var(--sticky-ink);border-radius:6px;padding:8px 12px;font-size:.9rem;margin-bottom:14px}

/* faq */
details{background:var(--paper);border:1px solid var(--line);border-radius:12px;padding:14px 18px;margin-bottom:10px}
summary{cursor:pointer;font-weight:700}
details p{margin:.7em 0 0;color:var(--muted)}

/* signup */
.signup{background:var(--blue);color:var(--blue-ink);border-radius:24px;padding:40px;text-align:center}
.signup h2{color:var(--blue-ink)}
.signup form{display:flex;gap:10px;justify-content:center;flex-wrap:wrap;margin-top:16px}
.signup input{padding:12px 16px;border-radius:999px;border:0;min-width:260px;font:1rem var(--body);background:#fff;color:#23263a}
.signup .btn{background:#fff;color:#1d4ed8;border-color:#fff}
.signup small{display:block;margin-top:12px;opacity:.85}
footer{padding:36px 0 60px;color:var(--muted);font-size:.85rem;border-top:1px solid var(--line);background:var(--bg)}
footer p{max-width:60em}
.sr{position:absolute;left:-9999px}
@media (prefers-reduced-motion:reduce){*{transition:none!important;scroll-behavior:auto!important}}

/* 3D lab */
.lab{display:grid;grid-template-columns:1.4fr 1fr;gap:26px;align-items:start}
@media(max-width:860px){.lab{grid-template-columns:1fr}}
.lab-demo{position:relative;height:720px;max-height:90vh;border-radius:var(--r);overflow:hidden;border:1px solid var(--line);box-shadow:var(--shadow);background:#0e131e;display:grid;place-items:end center;padding-bottom:13%}
.lab-demo iframe{position:absolute;inset:0;width:100%;height:100%;border:0;display:none}
.lab-demo.on iframe{display:block}
.lab-demo.on .btn{display:none}
.lab-list{background:var(--paper);border:1px solid var(--line);border-radius:var(--r);padding:22px;box-shadow:var(--shadow)}
.lab-list ul{padding-left:1.1em;margin:0 0 14px}
.lab-list li{margin:.45em 0}
.lab-demo{background:#0e131e url(assets/prev/3d-poster.svg) center top/cover no-repeat}
.lab-demo::after{content:"";position:absolute;inset:0;background:rgba(10,14,26,.35);pointer-events:none}
.lab-demo .btn{position:relative;z-index:2;box-shadow:0 10px 30px -6px rgba(0,0,0,.6)}
.lab-demo.on::after{display:none}

.doc{max-width:860px}.doc h3{margin-top:1.6em}.doc .btn{margin-top:6px}