:root{
 --bg:#100d0a;--paper:#1b1611;--ink:#f2e9dd;--text:#ded1c2;--soft:#b8aa9a;--line:#3d3025;
 --teal:#edb667;--teal-bg:#342719;--coral:#f0af80;--coral-bg:#402c21;--purple:#d9c7ec;--purple-bg:#342839;
 --radius:4px;--shell:1180px;--gold:#edb667;--gold-strong:#ffc779;--display:Georgia,"Times New Roman",serif;
 --small:"Segoe UI",Arial,sans-serif
}
html{color-scheme:dark;scroll-padding-top:90px}body{background:var(--bg);color:var(--ink);font-family:var(--small)}
a{color:var(--gold)}a:focus-visible,button:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:2px solid #ffc779;outline-offset:4px}
h1,h2,h3{font-family:var(--display);font-weight:400;letter-spacing:-.035em}.skip{background:#f7e6cd;color:#140e09;z-index:20}.muted,.sub{color:var(--soft)}.lead{color:var(--text)}
.mast{position:sticky;top:0;z-index:10;background:#0e0b09f5;backdrop-filter:blur(12px);border-color:#32271c}
.bar{min-height:70px;gap:16px}.brand{letter-spacing:0;gap:10px}.brand .brandname{font:400 1.35rem/.94 var(--display);letter-spacing:-.03em}
.brand strong{font:700 .61rem/1.25 var(--small);letter-spacing:.17em;color:var(--gold);text-transform:uppercase;margin-top:6px}
.brand img{width:32px;height:32px}.mainnav{gap:4px}.mainnav a,.pdfnav{border-radius:2px;font-size:.82rem;font-weight:650;padding:9px 10px}
.mainnav a:hover,.mainnav a[aria-current]{background:#2b2117;color:var(--gold)}
.pdfnav{background:transparent;border:1px solid #675035;color:var(--gold);letter-spacing:.08em}.pdfnav:hover{background:var(--teal-bg)}
.foot{margin-top:74px;background:#0c0908;border-color:#493523}.foot>.shell{padding:35px 0}.foot .credit{color:#e5ccaa;font:400 1.12rem/1.2 var(--display);letter-spacing:0}.foot span{font-size:.71rem}.foot a{text-decoration:none}
#workspace{padding-top:39px}.kicker{color:var(--gold);font-size:.69rem;letter-spacing:.18em;font-weight:700}
.btn,.btn.light{background:#e8aa5a;color:#1c1209;border-radius:2px;font-weight:750;padding:10px 16px;min-height:43px;box-shadow:none}
.btn:hover,.btn.light:hover{background:var(--gold-strong);color:#1b130a}.btn.ghost,.hero .btn.ghost{background:transparent;color:var(--gold);border-color:#6a5136}
.btn.ghost:hover,.hero .btn.ghost:hover{background:#35261a;color:#ffe0ae}.tabs button{border-radius:2px}
.tabs button[aria-pressed=true]{background:#e8aa5a;border-color:#e8aa5a;color:#1c1209}
.panel,.tile,.lesson{box-shadow:none;border-radius:3px}.tile svg{opacity:.9}.search,.filters select{border-radius:2px}
.lesson:hover{background:#251c13;border-color:#886642}.lesson .serial{background:#342719;color:#efbf85;border-radius:2px}
.badge{border-radius:2px}.pair>div+div{color:#dac6b1}.pair:nth-child(even){background:#211a14}.fold{background:#211a14;border-radius:3px}
.callout{background:#322318;border-radius:0 3px 3px 0}.callout small{color:#e0c9ac}.figure img{background:#eaf3ed;border-radius:3px}.figure a{display:block}
.flash .answer,.timer{background:#342719;border-radius:3px}.timer.low{background:#4c281f;color:#ffd0c2}.choice,.resultline span{border-radius:3px}
.reader aside{top:89px}.pagetitle{margin-bottom:27px}.pagetitle h1{font-size:clamp(2.45rem,5vw,4.4rem)}.crumb{color:#baa68e}
.topic-panel h2{font-size:1.8rem}.panel h3,.lesson strong{color:var(--ink)}.source a{color:#edb667}
#workspace.home-shell{width:100%;padding:0}.wide,.hero-inner{width:min(var(--shell),calc(100% - 64px));margin-inline:auto}
.hero{position:relative;display:flex;min-height:clamp(620px,47vw,740px);border-radius:0;background:#100c09;box-shadow:none;isolation:isolate;align-items:center}
.hero .hero-art{position:absolute;inset:0;width:100%;height:100%;z-index:-2;object-fit:cover;object-position:50% 55%;animation:settle 1.4s ease-out both}
.hero:before{content:"";position:absolute;inset:0;z-index:-1;background:linear-gradient(90deg,#0b0806e8 0%,#0c0906b8 30%,#0d09064f 54%,#0e0a050b 100%),linear-gradient(0deg,#0d0906ea 0%,transparent 30%)}
@keyframes settle{from{opacity:.75;transform:scale(1.035)}to{opacity:1;transform:scale(1)}}
.hero-inner{padding:72px 0 51px}.herotext{padding:0;max-width:680px}.hero .kicker{color:#eabc80}.hero-kicker span{display:inline-block;padding:0 7px;font-size:.62em}
.hero h1{font-size:clamp(3.45rem,7.2vw,7.1rem);line-height:.93;letter-spacing:-.054em;max-width:none;margin:22px 0 16px;font-weight:400}
.hero h1 em,.home-section h2 em{font-weight:400;color:#efb768}.hero h1 em{display:block}.hero .sub{font-size:.94rem;margin:0 0 13px;color:#e0c8aa}
.hero .lead{max-width:41ch;font-size:1.06rem;color:#eee1d1}.hero .actions{margin-top:27px}.hero .btn.ghost{color:#f7e7d2;border-color:#a48662}
.hero-stats{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:17px;max-width:500px;margin-top:53px}
.hero-stats>div{border-top:1px solid #d6a46d66;padding-top:10px}.hero-stats b{display:block;color:#f7c984;font:400 1.52rem/1.2 var(--display);font-variant-numeric:tabular-nums}
.hero-stats span{display:block;font-size:.69rem;color:#f2e0c8;margin-top:2px}.hero-stats .translation{color:#c9b097;font-size:.64rem}
.fieldstrip{background:#17110d;border-block:1px solid #413022}.strip-inner{display:flex;align-items:center;gap:21px;overflow-x:auto;scrollbar-width:thin;padding-block:12px}
.strip-inner>b{font-size:.62rem;letter-spacing:.12em;color:var(--gold);white-space:nowrap}.strip-inner a{display:flex;align-items:center;gap:8px;white-space:nowrap;color:var(--ink);text-decoration:none;font-size:.77rem}
.strip-inner a span{color:#bc8b50;font-size:.63rem}.strip-inner a small{color:var(--soft);font-size:.69rem}.strip-inner a:hover{color:var(--gold)}
.home-section{margin-top:76px}.home-section h2{font-size:clamp(2.6rem,5.5vw,4.6rem);line-height:.99;margin:8px 0 13px;font-weight:400;letter-spacing:-.043em}
.home-section .muted{max-width:58ch}.home-sectionhead{gap:24px;margin-bottom:25px}.chips{display:flex;gap:6px;overflow:auto;scrollbar-width:thin;padding:4px;flex:0 0 auto}
.chip{white-space:nowrap;padding:8px 12px;border:1px solid #433424;background:#1b1510;border-radius:2px;color:#dacebf;font-size:.79rem;font-weight:650}
.chip:hover{border-color:#c18d50}.chip[aria-pressed=true]{color:#25170d;background:#e7ae63;border-color:#e7ae63}
.feature-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:12px}.feature{min-width:0;display:block;background:#1b1510;border:1px solid #392b20;text-decoration:none;color:var(--ink);overflow:hidden;transition:border-color .2s,transform .2s}
.feature:hover{border-color:#b17e49;transform:translateY(-3px)}.feature-visual{height:117px;position:relative;background:#4c4132;overflow:hidden;isolation:isolate}
.feature.chemistry .feature-visual{background:#442718}.feature-visual img{width:100%;height:100%;object-fit:cover;object-position:center 58%;mix-blend-mode:luminosity;opacity:.56;transition:transform .4s ease,opacity .4s}
.feature:hover img{transform:scale(1.05);opacity:.74}.feature-visual:after{content:"";position:absolute;inset:0;background:linear-gradient(0deg,#1d140eb5,transparent 70%);pointer-events:none}
.feature-badge,.feature-serial{position:absolute;z-index:1;top:10px;padding:4px 7px;background:#17110eea;color:#f0cc9d;font-size:.62rem;font-weight:700;letter-spacing:.13em}
.feature-badge{left:10px}.feature-serial{right:10px}.feature-copy{padding:14px 15px 15px}.feature-copy h3{font-size:1.35rem;line-height:1.12;letter-spacing:-.025em}
.feature-copy p{font-size:.8rem;color:var(--soft);margin:5px 0 14px}.feature-link,.wing-bottom{color:var(--gold);font-size:.75rem;letter-spacing:.08em;font-weight:700}
.index-foot{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-top:13px;font-size:.78rem}.index-foot .actions{margin:0}
.engraving{margin:71px auto -1px;display:grid;gap:6px;width:min(80%,930px);opacity:.66}.engraving i{height:1px;background:linear-gradient(90deg,transparent,#8c6035 9%,#d49856 50%,#8c6035 91%,transparent)}.engraving i:nth-child(2),.engraving i:nth-child(4){opacity:.58}
.notebook-work{display:grid;grid-template-columns:1.07fr .93fr;gap:clamp(24px,5vw,72px);align-items:center}
.notebook-photo{position:relative}.notebook-photo img{width:100%;height:clamp(300px,36vw,440px);object-fit:cover;display:block}.photo-index{position:absolute;bottom:0;left:0;right:0;padding:13px 15px;color:#ffdeaa;background:#120d09db;font-size:.67rem;font-weight:700;letter-spacing:.14em}.photo-index span{float:right}
.steps{margin-top:22px;border-top:1px solid #4c3825}.steps>div{display:grid;grid-template-columns:35px 1fr;align-items:baseline;border-bottom:1px solid #4c3825;padding:10px 0}
.steps b{font-size:.74rem;color:var(--gold);font-variant-numeric:tabular-nums}.steps h3{font-size:1.3rem}.steps h3 small{font:400 .72rem var(--small);color:var(--soft);letter-spacing:0}
.steps p{font-size:.84rem;color:var(--soft);margin:4px 0}.wing-grid{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:10px}
.wing{color:var(--ink);text-decoration:none;background:#1b1510;border:1px solid #413024;min-width:0;overflow:hidden;display:flex;flex-direction:column;transition:border-color .2s,transform .2s}
.wing:hover{border-color:#b17e49;transform:translateY(-3px)}.wing img{height:142px;width:100%;object-fit:cover;display:block}.wing-copy{padding:14px;display:flex;flex-direction:column;flex:1}
.wing h3{font-size:1.5rem;margin:4px 0}.wing p{font-size:.75rem;color:var(--soft);margin-bottom:13px}.wing-bottom{margin-top:auto;border-top:1px solid #493625;padding-top:9px;display:flex;justify-content:space-between;gap:5px;font-size:.67rem;letter-spacing:0}
.exam-work{display:grid;grid-template-columns:1fr .92fr;gap:clamp(25px,5vw,69px);align-items:center;padding:32px 0;border-block:1px solid #483626}
.exam-ledger{background:#1c1611;border:1px solid #483626}.exam-ledger>div{display:grid;grid-template-columns:28px minmax(0,1fr) 28px;align-items:center;gap:10px;padding:11px 15px}
.exam-ledger>div+div{border-top:1px solid #483626}.exam-ledger b,.exam-ledger strong{font-size:.76rem;color:var(--gold);font-variant-numeric:tabular-nums}.exam-ledger strong{text-align:right}
.exam-ledger span>span{display:block;font-size:.86rem}.exam-ledger span>.translation{font-size:.7rem;color:var(--soft)}
.home-resources{display:flex;justify-content:space-between;gap:20px;align-items:center;margin-top:55px}.home-resources h2{font-size:clamp(2.35rem,4.6vw,3.6rem)}.resource-links{display:flex;gap:8px;flex-wrap:wrap}
.model-list{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:10px;margin-top:12px}.model-card .kicker{font-size:.62rem}.model-card h3{font-size:1.25rem;margin:7px 0}.model-card p{font-size:.84rem;color:var(--soft)}.model-card p[lang=en]{font-size:.79rem;margin-top:5px}.model-card .actions{margin-top:12px}.model-card .btn{font-size:.78rem}.model-card .model-topic{font-size:.76rem}.study-3d .actions{margin-top:12px}
@media(max-width:950px){.wide,.hero-inner{width:calc(100% - 44px)}.mainnav a{padding-inline:7px}.home-sectionhead{align-items:flex-start;flex-direction:column;gap:12px}.feature-grid,.model-list{grid-template-columns:repeat(2,minmax(0,1fr))}.wing-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.hero{min-height:590px}}
@media(max-width:680px){.mast{position:static}.bar{padding:9px 0;gap:9px;min-height:0}.mainnav a{padding:6px 7px;font-size:.77rem}.brand .brandname{font-size:1.2rem}.brand strong{font-size:.56rem}.brand img{width:29px;height:29px}.pdfnav{padding:6px 9px}.wide,.hero-inner{width:calc(100% - 34px)}
 .hero{min-height:565px;align-items:flex-end}.hero .hero-art{object-position:66% 45%}.hero:before{background:linear-gradient(0deg,#100c09 1%,#100c09ee 29%,#100c09ac 58%,#100c0952 100%),linear-gradient(90deg,#100c09b8,transparent 82%)}
 .hero-inner{padding:48px 0 28px}.hero h1{font-size:clamp(3rem,12.3vw,4.7rem);margin:15px 0 12px}.hero .lead{font-size:.95rem}.hero .sub{font-size:.83rem}.hero .actions{margin-top:19px}
 .hero-stats{gap:8px;margin-top:32px}.hero-stats b{font-size:1.29rem}.hero-stats span{font-size:.64rem}.hero-stats .translation{font-size:.62rem}
 .strip-inner{gap:14px;padding-block:10px}.strip-inner a small{display:none}.home-section{margin-top:48px}.home-sectionhead{margin-bottom:13px}.chips{width:100%;margin-left:-4px}
 .feature-grid{gap:8px}.feature-visual{height:89px}.feature-badge,.feature-serial{top:6px;font-size:.54rem;letter-spacing:.05em;padding:3px 5px}.feature-badge{left:6px}.feature-serial{right:6px}.feature-copy{padding:10px}.feature-copy h3{font-size:1.11rem}.feature-copy p{font-size:.73rem;margin-bottom:9px}
 .index-foot{align-items:flex-start;flex-direction:column}.index-foot .btn{font-size:.77rem;min-height:39px;padding:8px 10px}.engraving{margin-top:48px}
 .notebook-work,.exam-work{grid-template-columns:1fr;gap:22px}.notebook-photo img{height:255px}.home-resources{display:block}.resource-links{margin-top:13px}.wing img{height:105px}.wing-copy{padding:10px}.wing h3{font-size:1.28rem}.wing-bottom{font-size:.62rem}
 .model-list{grid-template-columns:1fr}.foot{margin-top:45px}.foot>.shell{padding:22px 0}.foot .credit{flex-basis:100%}.reader aside{position:static}.topic-panel h2{font-size:1.58rem}#workspace:not(.home-shell){padding-top:24px}
}
@media(max-width:360px){.feature-grid{grid-template-columns:1fr}.feature-visual{height:100px}.hero .actions{gap:7px}.hero .btn{font-size:.78rem;padding-inline:9px}.mainnav a{padding-inline:4px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation-duration:.01ms!important;transition-duration:.01ms!important;scroll-behavior:auto!important}}
@media print{html{color-scheme:light}body,.panel,.fold,.callout,.pair:nth-child(even){background:white;color:#14100c}a,.kicker,.muted,.sub,.pair>div+div,.callout small{color:#352a23}}
.molecular-control{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin:13px 0;font-size:.83rem;color:var(--soft)}.molecular-control select{min-height:43px;max-width:100%} #shape-info{margin-top:13px}

.reading-refs{margin:10px 0 0;padding:0;list-style:none}.reading-refs li{padding:9px 0;border-top:1px solid var(--line);font-size:.81rem}.reading-refs li strong,.reading-refs li span,.reading-refs li small{display:block}.reading-refs li span{color:var(--gold);margin-top:2px}.reading-refs li small{color:var(--soft);margin-top:2px}

.molecular-option{display:inline-flex;gap:8px;align-items:center;margin:0 0 11px;font-size:.81rem;color:var(--soft)}.molecular-option input{accent-color:var(--gold)}#shape-info>p{padding:8px 12px;font-size:.78rem}